y g o o m l a h t h p O l Color vision and color blindness For normal color vision we require cone photopigments sens itive to blue, green, and red light. The commonest hereditary color vision defect is X- lin ked failure of red \200\223green discrimination (8% \200 and 0.5% \200 aff ected \200 \224so those with Turner \200\231s syndrome have \200 incidence and those with Klinefelte r \200\231s have \200 incidence). Blue \200\223yellow discriminatory failure is more comm only ac- quired and sexes are aff ected equally. Diagnosis: This is by use of colored patte rn discrimination charts (eg Ishi- hara plates, see endpapers). Depressed color vision may be a sensitive indi- cator of acquired macular or optic nerve disease. Monochromatism This may be due to being born without cones (resulting in low visual acuity, absent color vision , photophobia, and nystagmus), or, very rarely, due to cone monochromacy where all cones co ntain the same visual pigment, when there is only failure to distinguish color. Drugs and the eye The eye does not retain drops for as long as ointments and 2-hourly appli ca- tions may be needed. Eye ointments are well-suited for use at night and when crusting a nd sticking of the lids occurs. Allow 5min between doses of drops to prevent overspill. The antibiotic drops most used are not those generally used systemically, eg fusidic acid, chl oramphenicol, neomycin, and framycetin. All eye preparations have warnings not to use for m ore than one month. Mydriatics (=cycloplegics) These dilate the pupil. They also cause cycl ople- gia and hence blur vision (warn not to drive). Pupil dilatation prior to exami- natio n is best achieved using 0.5% or 1% tropicamide which lasts for 3h. 1% cyclopentolate has a n action of 24h and is preferred for producing cyclople- gia (paralysis of the ciliary musc le) for refraction of children. These drugs may be used to prevent synechiae formation in a nterior uveitis. \200\207Over-60s with shallow anterior chambers (especially if a family h istory of glaucoma) may have acute glaucoma triggered, so only use on ophthalmological advi ce. Miotics These constrict the pupil and increase drainage of aqueous. They are used in th e treatment of acute glaucoma (p430). Local anesthetic Tetracaine (0.5% drops) is an exampl e, used to permit examination of a painful eye where re \202 ex blepharospasm is a problem , and to facilitate removal of a foreign body. \200\207It abolishes the corneal re \202 e x so use to treat pain is to risk corneal damage. To relieve pain, give an eye pad, and be generous with oral analgesia. In children use proxymetacaine (it stings less). Steroid and NSAID drops \200\207Steroids are very useful in managing ophthalmic in \202 ammation. The y are dangerous as they may induce catastrophic progres- sion of dendritic ulcers (p416). O phthalmoscopy may miss dendritic ulcers, and slit lamp inspection is essential if steroid d rops are being considered, eg for allergy, episcleritis, scleritis, or iritis. Steroid drop s \200\200intraocular pressure (newer drops less so: eg rimexolone has a low IOP-elevating potential, compa- rable to \202 uorometholone and < dexamethasone & prednisolone acetate ). 152 NSAID drops, eg ketorolac, may obviate the need for some steroid drops. 153 Iatrogen ic eye disease Allergic reactions may damage conjunctiva & cor nea, eg toxic epidermal necr olysis ( \201 g 2, p601) in aspirin allergy (Lyell \200\231s syndrome). Another type of to xic reaction is nystagmus indicating phenytoin toxicity. Dry eyes: Propranolol and oxprenol ol are typical culprits. Corneal deposits: Amiodarone, chloroquine, chlorpromazine, and gol d. Lens opacities: Steroids (including high-dose inhaled) are the typical culprits. Glaucom a: Typical culprit: steroid drops (above), mydriatics and anticholin- ergics (some antipark inson drugs and tricyclics). Papilloedema: Tetracyclines; nalidixic acid; steroids; the Pil l. Retinopathy: The drugs below are culprits if used chronically. \200 Vigabatrin. \200 Ethambutol: Warn patients to report any visual side-eff ects (loss of acuity, color blindn ess). 10% report new visual problems, and in 10% of these the cause is optic neuropathy (w hich may be irreversible).1 \200 Isoniazid: \200\201Red-green perception; pyridoxine co- administration prevents this. \200 Chloroquine (CQ)/hydroxychloroquine (HCQ) can cause (u ntreatable) retin- opathy if high doses are used. Risk of toxicity increases sharply toward s 1% after 6yrs of use, or a cumulative dose of 1000g of HCQ. Risk increases with continued use. Most patients are routinely given 400mg of HCQ daily (or 250mg CQ). This is OK unless short stature (then dose by ideal body weight). Screening schedule: Baseline exam on start ing (maculopathy would be a contraindication). Start annual screening 5yrs (or sooner if th ere are unusu- al risk factors). Newer objective tests, such as multifocal electroretinogra m, spectral domain optical coherence tomography, and fundus auto \202 uores- cence, can be more sensitive than visual \201 elds (which remain useful).154 456 y g o o m a h t h p O l l 457 Obtaining and preparing antibiotic eyedrops Forti \201 ed guttate gentamicin is 15mg/mL (t he normal commercial gentamicin is 3mg/mL); penicillin 5000U/mL, meticillin 20mg/mL, and an tifungals can be obtained from the Chief Pharmacist, Moor \201 elds Eye Hospital (tel. 020 725 33411). Antibiotics can be home-made as follows: Gentamicin forte: Add 2mL of 40mg/mL IV gentamicin to a 5mL bottle of commercial guttate gentamicin (3mg/mL).2 Other antibiotics can be made up using IV preparations to the required concentration using water or normal saline. These are stable for the time recommended for IV solutions in the m anufacturers Data sheets. Penicillin G can be used up to 500,000U/mL. y g o o m l a h t h p O l Eyedrops as a cause of systemic symptoms Drugs applied to the eye may be absorbed through t he cornea and pro- duce systemic side-eff ects \200\224eg bronchospasm or bradycardia in su scepti- ble individuals using antiglaucoma \200 -blocking drops, eg timolol, carteolol, be taxolol \200\224which is cardioselective. \200\207Symptoms may be subtle and insidi- ous \200\224eg gradually decreasing exercise tolerance, or falls from arrhythmias. Serious prob lems are more likely if there is co-morbidity (eg respiratory infection). Other anti-glaucoma drops (p440) cause headaches, and a bitter taste in the mouth; urolithiasis is reported with dorzolamide. Pilocarpine may cause parasympathetic swe ating. Accommodation spasm may lead to brow-ache (worse if <40 years old, or just starting treatment). Other SE: \200\231 \202 u-like syndrome, sweating, urinary frequency; more ra rely: urinary urgency, D&V (or constipation \202 atulence), dyspepsia, \202 ushes, BP \200\200, palpita- tions, rhinitis, dizziness, lacrimation, conjunctivitis, visual disturb ances, ocular pain, rash, pruritus. Even highly selective \200 2-receptor agonists used in glaucoma, eg brimonidine, can cause eff ects such as dry mouth (in 33% of patients), headache, hyperten- sion, fatigue, and dr owsiness. 155 1 Ethambutol eye problems: \200\201acuity (65%), \200\201 visual \201 elds (65%), abnor mal color vision (61%), optic disc pallor (38%), \200\200latency on visual evoked potentia l (65%). 30% showed improved vision on stopping etham- butol in one Korean study; latency for recovery: 5.4 1.7 months. No one with optic disc pallor at the time of diagnosis of optic neuropathy showed visual function improvement.@19145123 2 Mr J Dart FRCS, Moor \201 elds Eye Hospital; see also ncbi.nlm.nih.gov/pmc/articles/PMC2417514/?page=1 Contact lenses 80% of contact lenses are worn for cosmetic reasons. Only 20% are worn becau se lenses are better for the eye condition than spectacles. Among this 20% a minority wear the lenses to hide dis \201 guring inoperable eye conditions, a greater proportion have th em for very high refractive errors. Myopia above \200\22312 dioptres and hypermetropia abo ve +10 dioptres are indications for lenses because equivalent spectacles produce quite dist orted visual \201 elds. Lenses are used for ocular reasons, eg after corneal ulceration o r trauma when a new front surface of the cornea is needed to see through, and in keratoconu s.1 Types of lens Hard lenses are 8.5 \200\2239mm in diameter and are made of polym- ethylm ethacrylate (PMMA). Gas-permeable hard lenses are about 0.5cm larger and are designed to al low gas to permeate through to the underlying cornea. They can only be made to cope with a limited degree of astigmatism and do not wet as well as standard hard lenses, so may mist u p in the day. With the advent of the larger (13 \200\22315mm diameter) soft contact lenses it was hoped that many of the problems with hard lenses could be circumvented. Soft dispos- able lenses can be worn during the day for up to 4 weeks and then disposed of. Special con tact lenses called toric lenses can be used to correct astigma- tism of up to 2 dioptres. W ith more astigmatism, correction is not achieved because the lens \201 ts the astigmatic cornea taking on its shape. They are more delicate than hard lenses and need meticulous cle aning. Extended wear-lenses can be worn for up to 4 months. Sometimes colored lenses are us ed simply to change eye color. Disposable contact lenses are now more common. 458 y g o o m a h t h p O l l Patients may suff er from keratoconjunctivitis or giant papillary change in the upper tarsa l conjunctiva, possibly due to sensitization to the cleansing materials used or to the mucu s which forms on the lens. Cleaning lenses Cleaning solutions made by diff erent manufactur ers should not be mixed. With hard lenses 2 solutions are usually used, one for rinsing and cleaning, and one for storage. The storage solution should be washed off before the lens i s inserted. Soft contact lenses, being permeable, tend to absorb chemicals, so weaker solut ions for cleaning are used (also, lenses are usually intermittently cleaned with another sy stem, eg enzyme tablets, to remove mucoprotein on their surface). Sensitivity to cleaning a gents usu- ally presents as redness, stinging, increased lens movement, increased mucus pro duction, and thickened lids. It may be necessary to stop wearing lenses for several months. When restarting, use a preservative-free cleansing system. Can I reuse my daily disposable contact lenses (DDCL)? No! Overnight storage in blister-pack saline results in contaminate d lenses and infections (esp. staphs and esp. in men). We must educate patients in correct use of DDCL. Complications 1 Despite a shift to using of frequent-replacement daily-wear co ntact lenses, corneal ulcer is still a real problem, eg from Pseudomonas aeruginosa; o \202 oxacin drops have a role when suspected. 2 Corneal abrasion is common early while adjusting to wear. Pain lacrima- tion occurs some hours after removing the lens. 3 Sensitization to cleaning agents staining, eg by rifampicin or \202 uorescein. Eye ointments must not be used, nor eye-drying drugs. See BNF. 4 Losing the lens within the eye. Hard lenses may be lost in any fornix, soft lenses are usually in upper outer fornix. 5 Keratitis and risk of acanthamoeba infection (see BOX). iContacts Futuristic contact lens es with a tiny aerial and embedded pixels have already been tested in Finland. 156 Whether these will enable you to read constantly updated pages from OHCS while you jog remains to b e seen. 459 Hygiene and wear tips \200\207Pay attention to contact lens containers, as well as lenses. \200\207Do not assume that because a person uses disposable lenses there can be no nasty acanthamoebae infections. These free-living protozoa (found in soil and water, including ba throom tap water) may cause devastating keratitis even with disposable lenses. Scrub container \200\231s inside with cotton wool bud moistened with lens \202 uid. \200 Disinfect the container with hot water ( \211 80 C); leave to dry in open air. \200 Wa sh your hands before handling the contact lens container. \200 Replace the container at l east every year. \200 Protozoa may survive new \200\2301-step \200\231 solutions of 3% h ydrogen peroxide. Amoebae are diffi cult to treat, and there is current interest in salicyl ate \200\231s potential to reduce microbial attachment when used in contact lens care solut ions. 157 \200 Follow instructions about getting used to extended wear. Most corneal ul- cers from contact lenses are in people who are not used to extended wear and sleep overnigh t with their contact lenses in, or napped with them on a plane, or elsewhere for as little as 2 \200\2233 hours. y g o o m l a h t h p O l 1 In keratoconus the cornea bulges and is somewhat conical on lateral viewing. Vision is di storted. Multiple images and sensitivity to light can greatly impact on life, even if acuit y is unaff ected. 158 Other causes apart from ill- \201 tting contact lenses: UV exposure; LASIK complications (p464) compulsive eye- rubbing; 159 Down \200\231s syndrome. NB: idiop athic keratoconus entails chronic, nonin \202 ammatory, degenerative thinning of the corne a starting in young adulthood. Atopy and oxidative stress in the cornea may be im- portant Susceptibility locus: SNP rs4954218, near RAB3GAP1 gene. Treatment: rigid gas permeable con tact lenses are employed to vault over the cornea, replacing irregularities with a smooth, uniform refracting surface. This is often insuffi cient, and keratoconus is a leading reaso n for corneal transplantation. Blepharospasm Blepharospasm is involuntary contraction of orbicularis oculi. It commonly oc curs in response to ocular pain. Repetitive blepharospasm, which may have a serious impact on quality of life, or make the patient eff ectively blind, is a focal dystonia (OHCM p473) . If the condition is not recognized, it is all too easy to dismiss the patient as hysteric al and to think that screwing up of the eyes is deliberate \200\224especially, the more the skeptical doctor questions and probes the affl icted patient, the worse the blepharospasm may become (stress is an important exacerbating factor). It is important to understand that it may have a serious negative impact on patients \200\231 lives. 160 Presentation \200 : \200 \211\210 1.8 : 1. Blepharospasm is often preceded by exaggerated blinking. Other dy stonias may be present (eg oro-mandibular). It usually starts unilaterally, becoming bilate ral. Patients may develop tricks to reduce it such as touching or pulling the eyelids \200 \224a variation of geste antagoniste seen in other forms of dystonia. Causes: (Mostly unkno wn.) Neuroleptic drugs, Parkinson \200\231s disease, progressive supranuclear palsy, parane oplastic (p589, eg from lung ca). Treatment Drugs: Botulinum neurotoxin: Palliation is achi eved with small doses injected to orbicularis oculi; here it produces a temporary \202 ac cid pa- ralysis. It can help some people recover eff ective vision. It binds to peripheral nerve terminals and inhibits release of acetylcholine. 3-montly treatments are needed. Resp onse is variable; good eff ects may wear off . Other options: anti- cholinergics (trihexyph enidyl, eg 1mg/day PO, max 5mg/6h; tablets are 2mg or 5mg). Dopamine agonists (L-dopa, brom ocriptine) may help. Supportive treatment: If the cause is compensation for apraxia of lid opening, wearing goggles may help. 161 See also the UK Dystonia Society, tel: 0207 329 0797 . 460 y g o o m a h t h p O l l Allergic eye disease Seasonal allergic conjunctivitis and peren- nial allergic conjunctivit is head the list (BOX 2), followed by atopic keratoconjunctivitis (AKC), giant papillary co njunctivitis and oth- er rarer conditions. Sight-threatening vernal keratoconjunctivitis is described below. Vernal keratoconjunctivitis (VKC) com- prises 0.5% of allergic eye diseas e. It begins as a type I hypersensitivity reaction; later there are in \201 ltrates and a type IV reaction. Typical patient: An atopic boy (<14yrs old) from warmer climes with sever e bilateral symptoms in spring: itchy eyes, blepharos- pasm, foreign body sensation, photop hobia, tearing (lid skin is spared, unlike in AKC, see BOX). \200 : \200 \211\210 2 : 1. VKC often resolves spontaneously soon after puberty. Signs: Thick mucoid discharge from la rge conjunctival papillae, eg under the upper lid ( \201 g 1) and enough to cause ptosis; when \202 attened they look like cobble- stones. Corneal perilimbal papillae may occur. C onjunctival scarring and plaques occur. The cornea can erode, forming sight-threatening shi eld ulcers ( \201 g 1). 162 \201\227: Start with drops, eg olopatadine or lodoxamide (BOX 1). If uncontrolled or if corneal disease develops, steroid drops are needed (eg 1% predni solone acetate/2h; taper rapidly). Ciclosporin drops (1 \200\2232%) also help VKC. 163 Corn eal involvement needs careful eye clinic review and often coverage with steroids, antibioti c drops and lid hygiene to limit staphylococcal colonization. If severe blepharitis, oral e rythromycin or doxycyline (in adults) can help. Topical lubri- cants also help soothe eyes and washout allergens. Fig 1. Giant papillae & superior gray oval corneal ulcer ( \200\230shield \200\231 ulcer) i n VKC. Courtesy of Mr D Tole FRCOphth. 3 principles for successfully managing allergic eye disorders 164 1 Remove the allergen res ponsible where possible ( \200\234don \200\231t travel to places 461 which make your symptoms worse \200\235). 2 General measures: \200 Cold compresses \200 Arti \201 cial tears to wash out al- ler gens and \200\201itch \200 Oral antihistamines for symptom relief, eg loratadine 10mg/d PO \200 Nasal steroid sprays may help even if no nasal symptoms. 165,166 3 Eye-drop speci \201 cs (rapid action + fewer SEs , being topical) \200\224eg anti- histamines (eg azelas tine), drugs inhibiting mast cell degranulation (cromoglicate; lodoxamide), and accessory d rugs, eg steroids (eg dexa- methasone; beware inducing glaucoma), NSAIDs (eg diclofenac) , 167 immu- nosuppressants (ciclosporin, specialist use only), and vasoconstrictors (eg xyl ometazoline \200\224not very eff ective and may cause rebound hyperaemia). y g o o m l a h t h p O l Allergic conjunctivitis and associated conditions Acute allergic conjunctivitis is caused b y an IgE mediated type 1 hypersen- sitivity, triggering release of in \202 ammatory mediat ors by mast cells. 168 Most have a history or family history of atopy (eg asthma or eczema) . Chronic allergic disorders are characterized by an increase in the number of the local conj unctival T-cell population with a mixed cellular in \201 ltrate of mast cells, eosinophils , neutrophils and macrophages. Seasonal allergic conjunctivitis (SAC) Up to 50% of allergic eye disease. Symptoms are seasonal and mild \200\224but may continue long after allergen e x- posure. 166 Examination shows small papillae on the tarsal conjunctiva. It is self limit ing and not sight threatening. \201\227: Antihistamine drops, eg ketotifen, azelastine, ep inastine, emedastine, or olopatadine. 2nd line: diclofenac 0.1% drops. 169 Mast cell stabil izers may be used prophylactically. 170 Perennial allergic conjunctivitis (PAC) Symptoms ar e mild and may persist all year with seasonal exacerbations. Small papillae are found on th e tarsal conjunctiva. Management: Prescription drops: olopatadine (antihistamine and mast c ell stabilizer), lodoxamide or nedocromil (mast cell stabilizer). Over-the-counter drops: s odium cromoglicate 2% (/6h). 171,172 Atopic keratoconjunctivitis (AKC) aff ects 1.5% of the population and is potentially sight threatening. Symptoms are severe with pain, redness, a nd reduced vision. Signs include conjunctival papillae and eventual conjunctival scarring w hich can lead to corneal opaci \201 cation and neovascularization. Atopic blepharoconjunct ivitis (ABC) is similar to AKC but with associated blepharitis (lid margin in \202 ammatio n) and limited corneal involvement. Giant papillary conjunctivitis Giant papillae on the ta rsal conjunctiva is an iatrogenic condition related to foreign bodies, eg contact lenses, o cular prosthesis and sutures. Management: Involves removal of the foreign body and treatmen t with topical mast cell stabilizers or steroids. Contact dermatitis This describes erythem a of the skin surrounding the eye. It is a reaction to a particular antigen. This is not si ght threatening. Phlyctenular keratoconjunctivitis This may be a delayed response to myco b acteria, staphs, yeasts, or chlamydia. The conjunctival phlyctenule be- gins as a hard, red , 1 \200\2233mm diameter papule surrounded by hyperaemia. At the limbus, it is triangular ( apex points to cornea). It ulcerates, and then subsides within 12 days. Corneal phlyctenule s develop as an amorphous gray in \201 ltrate, and leave a scar. They may cause intense ph otophobia. Management: Get help. Steroid drops may help. Treat any bacterial cause. 173 Floaters, \202 ashes (photopsia), and haloes Lots of \202 ashes may indicate the mo- me nt of a retinal tear or detachment; lots of \202 oaters suggest blood or pig- ment releas ed into the vitreous. 462 octor, you say there are no haloes around the streetlights in Paris and what I see is an ab erration caused by old age, an affl iction. I tell you it has taken me all my life to arriv e at the vision of gas lamps as angels. \201\201 \200\230Halo \200\231 refers to a circle of light, white or colored, seen around any lumin ous body (not just saints). Also Lisel Mueller: Monet Refuses the Operation M Faith McLella n 1996. Lancet 1996 348 1641 call to mind Monet, his cataracts (a cause of haloes) and his paintings and their \200\230investments in light \200\231 (another meaning of halo). In th e poem, Monet refuses surgery for his cataracts: how diff erently doctors and artists see t he world (BOX 1)! So before we advise surgery it \200\231s wise to get to know our patients , and to keep a eye on posterity. Floaters they are often caused by RBCs (anything that cau ses new vessesl to form on the retina can lead to vitreous hemorrhage and perceived \202 oaters (diabetic retinopathy; vein occlusions) trauma/retinal detachment (often with blood in the vitreous). White cells are the other main cause, eg from in \202 am- matory/infecti ve causes, posterior choroiditis (p438). Sinister causes are sec- ondary to tumor seeding \200\224either primary as in melanoma or retinoblastoma (patients often too young to compla in of symptoms) or secondary metastasis. Also think of endophthalmitis (eg fungal). Degener ative causes include opaci- ties in the vitreous: asteroid hyalosis (like stars in the nigh t sky) and syneresis (here, each \202 oater is a shadow of a mobile vitreous opacity cast on the retina. After the eye comes to rest, they continue to move \200\224they are common in my- opes, after cataract surgery or after trauma. y g o o m a h t h p O l l Floaters present as small dark spots in the visual \201 eld, particularly noticeable agai nst a bright background. Often, they are just annoying (if central), but harmless, and may settle with time. Examine the vitreous and retina before reassuring. Sudden showers of \202 oaters in one eye ( \202 ashing lights) may be due to blood. \200\207Refer immedi ately (for specialist assessment within 48h or sooner): the cause may be retinal detachment (p444). Flashing lights (photopsia) Either from intraocular or cerebral pathology (migrain e). Is there headache, nausea, or previous migraine? Detachment of a shrinking vitreous fro m the retina gives \202 ashes and \202 oaters. 5% go on to retinal tears and detachment . Retinal damage is usually peripheral and hard to see \200\224refer immediately for specia list help. 4 \200\230F \200\231s of retinal detachment \200 Floaters (numerous, acute on set, constant, and described as \200\230spider \200\231s web \200\231 \200 Flashes \200 Field loss (acute, progressive) \200 Fall- ing acuity. See p444. Posterior vitreous det achment (PVD) Degenerative changes in the vitreous lead to its eventual separation from the retina. This is part of normal aging. Patients describe monochromatic photopsia in the per ipheral temporal \201 eld. This is more obvious in dim light and with eye movements. Ther e is an increase in \202 oaters but vision remains unchanged and there are no \201 eld defects. Refer for fundus check as retinal tears can happen as a consequence of the PVD. Ha loes Smooth, colored haloes around lights are diff ractive phenomena, be- ing seen when a w hite light is inside a steamed-up window (street lights have haloes when seen through miste d windscreens), or through scratched spec- tacles. Hazy ocular media may also be the cause (cataract; corneal oedema). In acute angle closure glaucoma it is corneal oedema that cause s them as intraocular pressure rises with pupillary dilatation. If haloes are accompa- nied by eye pain consider this diagnosis and refer immediately. Jagged haloes which change shap e are usually due to migraine. Beware labeling haloes as migrainous in those >50yrs who hav e not previously suff ered from migraine. 463 Seen, unseen, and seer \200\224and the indiff erent pixel \200\234The greatest thing a hum an soul ever does in this world is to see something, and tell what it saw in a plain way. H undreds of people can talk for one who can think, but thousands can think for one who can s ee. \200\235John Ruskin Modern Interpreting but not over-interpreting our visual sensations entails the al- most impossible task of seeing the indiff erent pixels as well their patte rns. Is it a stone or a frog (genus Batrachus)? Is it a lea \202 ess (aphyllous) branch or a snake? As Eliot knew, when \200\234the eye adjusts itself to the twilight, the dead sto ne is seen to be batrachian, the aphyllous branch ophidian \200\235. When a classicist, rev ising for her exams, says \200\234I \200\231m preparing for my Unseen \200\235 she means \200\234I \200\231m preparing for a surprise. I \200\231m going to have to translate, with- out warning, some unknown ancient passage (our primordial unconscious) into modern parlanc e (current sensations). \200\235 To do well, she (and we) have to expect the unexpected, or else the snake will bite us. More deeply, all visual experience is ambiguous, yet we belie ve and act on it all the time. Seers, philosophers, and, above all, poets know that the iss ue here is the role our imagination plays in seeing. \200\234I have seen sometimes what me n imagine they see. \200\235 (J \200\231ai vu quelquefois ce que l \200\231homme a cru voir !) The Drunken Boat Arthur Rimbaud How is this important clinically? Just as we are born ex pecting to hear each other \200\231s voices, so we are born expecting to see each other \200\231s faces. If in later life we lose our vision, then the brain, with exaggerated zeal , compensates by creating \201 ctive visual percepts, almost always involving faces \200 \224a surpris- ingly common non-psychotic hallucination named after Charles Bonnet, who \201 rst described it in his 89-year-old grandfather in 1769. Charles Bonnet \200\231s gran dfather might say with insight: \200\234I have imagined sometimes what other men know they see \200\235 \200\224ie the mirror-image of Arthur Rimbaud \200\231s formulation. The poin t is that neither Rimbaud nor Bonnet can pinch themselves to see if their hallucinatory sta te is real. By their system- atic derangement of their senses they teach us something unive rsal about our place in our external and internal worlds, namely that we can never fully di sentangle what we see from what we expect to see. It is as if our pro- pensity for illusion s validates and authenticates our experience of being us. So don \200\231t get too annoyed with your patients when they give ambiguous an- swers to your questions about \202 oaters , \202 ashes and more complex \201 ctive visual percepts. Just smile to yourself and to Rimbaud in his embodiment as a drunken, waterlogged boat (Le bateau ivre) and remember tha t the boat is in the drink and the drink is in the boat. Painters; vol. III y g o o m l a h t h p O l Refractive procedures Refractive procedures are increasingly undertaken as an alternative t o wear- ing spectacles; mostly for cosmetic reasons. Occasionally they are undertaken for a nisometropia (imbalance of prescriptions); for astigmatism after surgery; or for intoleranc e of spectacles or contact lenses. A variation of PRK (photore- fractive keratotomy) may be undertaken for some corneal diseases. LASIK (see below) is now the commonest procedure. It is well researched and in terms of surgical procedures is extremely safe but there are pos sible complications. It should be noted that most ophthalmologists wear spectacles! Photore fractive keratotomy (PRK) This is an entirely laser treatment where the curved front of the cornea is altered by laser ablation. It is only done for low degrees of myopia and is less predictable than LASIK with some people having under-correction and others over-correction . Corneal haze with re- duced vision, glare, and haloes are occasional problems. In most lo w myopes it gives good outcome but it is very painful for a few days. LASIK (laser assisted in situ keratomileusis) This is a combination of minor surgery where the cornea is incised and an extremely thin trapdoor- shaped \202 ap hinged away and then excimer laser is app lied to the bare corneal stroma underneath. Thereafter the \202 ap is pushed back into po sition and ad- heres naturally. It is, surprisingly, virtually painless, settles very quick ly, and is fairly predictable in its outcome. Corneal sensitivity recovers after 6 months. A thin \202 ap with a nasally placed hinge is associated with the most rapid re- covery of corneal sensitivity. 174 It is possible to undertake surgery on much greater degrees of refractive error; with up to 5 dioptres of hypermetropia; 5 dioptres of astigmatism; and 15 dioptres of myopia (if >15, risk \200\200 \200\200). 175 Serious complications are rare b ut trauma to or infection of the \202 ap may result in per- manent corneal scarring. In o ne series of 779 eyes no serious, vision-threaten- ing, irreversible complication such as k eratectasia or progressive endothelial cell loss was observed (follow-up: 5yrs). Warn that improved acuity tends to wane over time. 176 Intraocular pressure often falls (eg by 4mmHg) . Note that LASIK tourism to \201 nd cheap surgery abroad is associated with problems suc h as corneal ectasia, \202 ap problems, keratitis, and under- and over-correction. 177 LA SEK (laser epithelial keratomileusis) This is diff erent from LASIK in that the corneal epi thelium is softened with an alcohol solution and lifted off . Laser is then applied to resh ape the cornea and the epithelium is carefully replaced. Epi-LASIK tries to give the best o f both LASIK and LASEK. A blunt blade is used to lift a 9mm-diameter \202 ap of epitheliu m as a single sheet with a nasal hinge. It retains its integrity as a properly-viable entit y. In this \200\230on- \202 ap \200\231 method, the \202 ap is repositioned and acts as a bandage while the underlying cornea heals. So far it looks as though \200\230off - \202 ap \200\231 methods (complete removal of all the \202 ap as in LASEK) and \200\230o n- \202 ap \200\231 epi-LASIK have equal visual and refractive outcomes in myopia, but oth er diff erences may declare themselves over time.178 Lens surgery Altering refraction by cl ear lens extraction with intraocular lens implantation with the appropriate corrective powe r is another option. Accommodation is lost, so reading needs correction. Another option is an in- traocular lens implanted in front of the human lens (phakic implant). Radial keratot omy This is historical and should no longer be done. It in- volved surgical incisions of th e peripheral cornea to alter the curvature. Other procedures These are much less commonly u ndertaken. They include insertion of perspex rings into the cornea; other laser techniques to alter cor- neal curvature; and surgery to the sclera to attempt to correct presbyopia. T hey are much less certain in outcome and are best regarded as experimental. 464 y g o o m a h t h p O l l This page intentionally left blank 466 6 Primary care \200 Giving yourself to the highest bidder? 468 A dictionary of primary care acronyms 469 Primar y care and health de \201 nitions 470 Primary care, self-care & intermediate care 472 Prim ary health care teams 474 Small practices or commercial GP clinics? 475 Time, time manageme nt, the busy GP stereo- type, and patient-centered care 476 Medical certi \201 cation 477 The consultation 478 The impossibility of being a good docto r 481 Prevention (and barriers) and screening 482 \200\2236 Primary care clinics 488 Eviden ce-based medicine 489 Protocols, targets, and guidelines 490 The placebo and Hawthorne eff ects 491 Bedside manners in a multicultural world 492 Health education: what \200\231s the point? 494 Patient groups 496 Patients \200\231 complaints & clinical governance 497 Dying at home (palliative care) 498 \200\223501 Records, computers, and decision support 502 Medl ine 504; Premonitions 505 Audit 506 New ways of extending primary care 507 Appraisal, reval idation, & performance 508 Under- and over-performing doctors 509 Patient satisfaction 510 Expert patients: plagues \200 or inspirations? 511 Stopping smoking tobacco 512 Reducing al cohol intake 513 Domestic violence 514 Sustainability & alternative/holistic medicine 515 L iving dangerously 516 Home visits (including one with Nietzsche) 516 Minor illness 517 Are you ready for emergencies/on call? 518 Prescribing and concordance 519 Healing 520 Social m atters 522 Health and social class 523 Purchasers & providers 524 Referral statistics 525 F itness to drive, \202 y, do sport etc 526 Chronic fatigue syndrome 528 Managing obesity 5 30 What to do for the best? 532 Relevant pages elsewhere \200\207Every page in all chapter s. This is why the above contents list is oddly starved of nice meaty clinical topics: don \200\231t worry: they all \201 gure hugely in primary care, but not here because just the list would overwhelm you. See also RCGP GP curriculum rcgp-curriculum.org.uk/extras/curric ulum/index.aspx Fig 1. The correct method for conducting morning surgery: don t look down; don t stop ped- alling. \200\234How do I do it? \200 If I did know what I m doing I wouldn t be able to do it. \200\2351 Is conducting morning surgery a performing art? There is no shortage of fa rce (or tragedy). Because of the huge and unde \201 ned range of primary care, it is said that GPs \200\230need to be the most comprehensively educated of any kind of doctor \200\231. We thank Dr Konstantinos Kritikos, our Junior Reader, for his contribution to this chapter. P \201\201 467 rimary care doctors are specialists in six areas: 1) Diagnosis 2) Health philosophy 3) Dise ase in its earliest phases 4) Prioritizing con \202 icting advice from organ-based special ists 5) Families and their inter- actions with disease 6) Prevention, and balancing of con \202 icting preventive duties. They are personal doctors, responsible for giving comprehen sive and continuing generalist care to those seeking medical help, irrespective of age, sex and state of health. \200\2252 They are the only doctors quali \201 ed to diagnose health and they have special knowledge and experience of disease in its ear- liest phases. They c an answer such questions as \200\234Why doesn \200\231t Miss Phelps ever attend the antena tal clinic? \200\235 and \200\234What must change for her to do so? \200\235. There are fe w instances where GPs can off er more skill and expertise than all other doctors, but there are many times when her understanding of her patient is what counts, and for which no amou nt of expertise can substi- tute. So when, Miss Phelps \200\231s baby dies, to whom does sh e turn in her dis- tress? She isn \200\231t a medical or obstetric problem; she isn \200 \231t even a psychiatric problem: she is Miss Phelps; and the doctor who specializes in her is her GP. \200 . s t e t r a u Q r u o F e r a c y r a m i r P , t o i l E S T \200 e r a c l a n r e t a p Knowledge of the patient and knowledge of disease (from its earliest to its terminal phases ) coupled with the ability to diagnose health (p470) is what comprises this unique discipli ne. If a patient is asking \200\234Am I well, or could I have cancer \200\235 the doctor w ho is always responding by saying \200\234Well, I \200\231m not sure \200 let \200\231s do one more test \200\235 is often a bad doctor, and al- ways an expensive one. Some doctor s have the gift of appraising a patient and knowing instinctively, when to treat, investiga te, refer, or reassure. Nowhere is this instinct more used than in primary care. A chest ph ysician may tell a person that his lungs are healthy, but if, on your way out, he says \200\234Oh, and I \200\231ve also got this pain in my leg \200 \200\235 she may feel out o f her territory. This new symptom undermines her and she is likely to end up saying \200 \234Go and see your GP \200\235, who must then somehow decide whether to reassure, treat, o r refer to another specialist. Coming to primary care after hospital medicine This may be y our \201 rst experience of taking sole responsibility for an episode of care. This may se em isolating, so take steps to make clinical friendships with like- minded staff . Ensure y our plans make sense to your patient. Does he know to return if there are unexpected develo pments? You may need to use time itself rather than some complex scan to make the diagnosis . If tests are needed, they can be done in logical order, rather than all at once which ten ds to happen in hospital. Cargoes of gold: Hospital medicine of- ten deals with a single pr oblem using overwhelming, awesome force (eg shocks, IV antibiotics, scalpels etc) and delig hts in eliminating problem num- ber one now. But primary care takes the long view, sometime s over gener- ations, and wont always try to solve a pressing problem, rather seeking to pr eempt its complications, to set it in context, and to arrange for patients and families to have a psychological advantage when dealing with illnesses that may be interacting in enigm atic ways. We may not say to man with a chest infection \200\234here \200\231s an antibiot ic and stop smoking 40 a day, you idiot \200\235 when we realize he is the partner of last week \200\231s exotic self-harming pa- tient whose psychosis is now mysteriously impro ving. Instead you may hear yourself saying to her: \200\234I think it \200\231s marvelous how you look after each oth- er here are some tips on helping him when his chest is bad . \200\235 Will she \201 nd her new role as reciprocal carer humanizing, and over time, w ill she realize that if she self-harms less he will smoke less? Maybe. Let \200\231s see. \201\201Primary care is full of such excitements, delayed fuses, exploding and unexploding bombs, and collateral blast injury (and delayed rewards, but only when done over years: kee p at it, and today \200\231s dull surgery may one day deliver its cargo of gold into your l ap.) This example embodies the ancient idea that your di- agnoses must be social, spiritual , and psychological, as well as physical. e t u l o s b a e h t f o e i d l l a h s e w , l l e w o d e w f i , n i e r e h w , e r i a n o i l l i m d e n i u r e h t y b d e w o d n e l a t i p s o h r u o s i