These blackfly, Simulium, usually dwell near fast-flowing African streams, so the disease is also called "river blindness". Classification (by stage of disease)
Superficial punctate keratitis
Ulcerative keratitis

Classification (by environmental aetiology)
Exposure keratitis (also known as exposure keratopathy) — due to dryness of the cornea caused by incomplete or inadequate eyelid closure (lagophthalmos). Photokeratitis — keratitis due to intense ultraviolet radiation exposure (e.g. snow blindness or welders arc eye.) Contact lens acute red eye (CLARE) — a non-ulcerative sterile keratitis associated with colonization of Gram-negative bacteria on contact lenses. Treatment
Treatment depends on the cause of the keratitis. Infectious keratitis can progress rapidly, and generally requires urgent antibacterial, antifungal, or antiviral therapy to eliminate the pathogen. Antibacterial solutions include levofloxacin, gatifloxacin, moxifloxacin, ofloxacin. It is unclear if steroid eye drops are useful or not.In addition, contact lens wearers are typically advised to discontinue contact lens wear and replace contaminated contact lenses and contact lens cases. (Contaminated lenses and cases should not be discarded as cultures from these can be used to identify the pathogen). Aciclovir is the mainstay of treatment for HSV keratitis and steroids should be avoided at all costs in this condition. Application of steroids to a dendritic ulcer caused by HSV will result in rapid and significant worsening of the ulcer to form an amoeboid or geographic ulcer, so named because of the ulcers map like shape. Prognosis
Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, endophthalmitis (an infection inside the eye), or even loss of the eye.
Laser treatment for acne might reduce comedones, but dermabrasion and laser therapy have also been known to cause scarring.Macrocomedones (1 mm or larger) can be removed by a dermatologist using surgical instruments or cauterized with a device that uses light. The acne drug isotretinoin can cause severe flare-ups of macrocomedones, so dermatologists recommend removal before starting the drug and during treatment.Some research suggests that the common acne medications retinoids and azelaic acid are beneficial and do not cause increased pigmentation of the skin. If using a retinoid, sunscreen is recommended. Rare conditions
Favre–Racouchot syndrome occurs in sun-damaged skin and includes open and closed comedones.Nevus comedonicus or comedo nevus is a benign hamartoma (birthmark) of the pilosebaceous unit around the oil-producing gland in the skin. It has widened open hair follicles with dark keratin plugs that resemble comedones, but they are not actually comedones.Dowling–Degos disease is a genetic pigment disorder that includes comedo-like lesions and scars.Familial dyskeratotic comedones are a rare autosomal-dominant genetic condition, with keratotic (tough) papules and comedo-like lesions. References
External links

Rines, George Edwin, ed. (1920). "Comedones" . Encyclopedia Americana. What causes blackheads, Treatment and Prevention Archived 2020-01-27 at the Wayback Machine