Once the loss has progressed to the 2–4 kHz range, there is increased difficulty understanding consonants. Both ears tend to be affected. The impact of presbycusis on communication depends on both the severity of the condition and the communication partner.Older adults with presbycusis often exhibit associated symptoms of social isolation, depression, anxiety, frailty and cognitive decline. The risk of having cognitive impairment increased 7 percent for every 10 dB of hearing loss at baseline. No effect of hearing aids was seen in the Lin Baltimore study. Causes
The aging process has three distinct components: physiologic degeneration, extrinsic damage (nosocusis), and intrinsic damage (sociocusis). These factors are superimposed on a genetic substrate, and may be overshadowed by general age-related susceptibility to diseases and disorders. Hearing loss is only weakly correlated with age. In preindustrial and non-industrial societies, persons retain their hearing into old age. In the Framingham cohort study, only 10% of the variability of hearing with age could be explained by age-related physiologic deterioration. Within family groups, heredity factors were dominant; across family groups, other, presumably sociocusis and nosocusis factors were dominant. Heredity: factors like early aging of the cochlea and susceptibility of the cochlea for drug insults are genetically determined. Oxidative stress
General inflammatory conditions

Sociocusis
Sociocusis is the condition of those who have hearing loss attributed to continuous noise exposures, unrelated to their job or occupation. This exposure to these stimuli is frequent, and are often considered common "background noises" that affect the hearing abilities of individuals.
Herpetic simplex keratitis is a form of keratitis caused by recurrent herpes simplex virus (HSV) infection in the cornea.It begins with infection of epithelial cells on the surface of the eye and retrograde infection of nerves serving the cornea. Primary infection typically presents as swelling of the conjunctiva and eyelids (blepharoconjunctivitis), accompanied by small white itchy lesions on the corneal surface. The effect of the lesions varies, from minor damage to the epithelium (superficial punctate keratitis), to more serious consequences such as the formation of dendritic ulcers. Infection is unilateral, affecting one eye at a time. Additional symptoms include dull pain deep inside the eye, mild to acute dryness, and sinusitis. Most primary infections resolve spontaneously in a few weeks. Healing can be aided by the use of oral and topical antivirals. Subsequent recurrences may be more severe, with infected epithelial cells showing larger dendritic ulceration, and lesions forming white plaques. The epithelial layer is sloughed off as the dendritic ulcer grows, and mild inflammation (iritis) may occur in the underlying stroma of iris. Sensation loss occurs in lesional areas, producing generalised corneal anaesthesia with repeated recurrences. Recurrence can be accompanied by chronic dry eye, low grade intermittent conjunctivitis, or chronic unexplained sinusitis. Following persistent infection  the concentration of viral DNA reaches a critical limit. Antibody responses against the viral antigen expression in the stroma can trigger a massive immune response in the eye.