Originally published in NKCf Update (June 2024).
Twelve years ago, an Australian optometrist posed an alarming observation. ‘Where,’ he asked, ‘were the older keratoconus patients?’ He observed few older keratoconus patients in his contact lens clinic and wondered if individuals with keratoconus died at a younger age. Other clinicians joined in the discussion and noted that medical conditions associated with keratoconus, like obstructive sleep apnea, obesity, or mitral valve prolapse may indeed shorten the lives of KC patients. The question was never satisfactorily answered.
Recently, researchers in Utah reviewed mortality data and causes of death using the Utah Population Database, which matches hospital health records with death certificates issued in that state. During the period 1996 to 2020, records associated with 7,847 individuals with keratoconus and 38,597 age, sex and race matched controls were selected for the study.
The mortality results between the KC and control groups were similar. At the conclusion of the study, 92% of the subjects with KC were still alive, 7.5% had died by natural causes, and 0.8% by unnatural causes (accident, suicide, or homicide). In the control group, the breakdown was 91% still alive, 7.9% died by natural causes and 0.9% by unnatural causes.
The cause of death in the two groups did not reveal unusual disparities. The authors noted that while KC has been associated with a number of systemic conditions, no red flags for cause of death emerged. For example, a condition linked to KC, obstructive sleep apnea, is associated with increased risk of cardiovascular events and stroke. It might be expected that keratoconus patients would suffer from above average cardiovascular deaths. Yet no increased mortality was identified.
Only one category showed a minor, but statistically significant difference: 72 individuals with keratoconus died from diseases of the nervous system or sense organs (0.9%) compared with 24` (0.6%) of the control group The authors could think of no systemic condition associated with keratoconus to account for this, and concluded additional study would be needed to determine if there was an underlying condition responsible.
When the alarm originally sounded about the absence of older patients in contact lens clinics, the author compared the mean age of non-KC patients with the mean age of keratoconus patients seen in selected doctors’ offices and feared a reduced life expectancy. In retrospect, it may be that older KC patients had given up on wearing contact lenses, or perhaps as these patients aged, the idea of traveling to a specialty clinic was too difficult and the patients were getting their eyesore elsewhere. Or perhaps they developed other age-related eye conditions such as a macular degeneration, glaucoma, and cataract, and were being managed by other eye doctors.
The Utah paper reassures us that individuals with keratoconus do not die earlier, or from causes that are any different than their neighbors.
References: McMonnies CW, Quo Vadis Older Keratoconus Patients? Do They Die at Younger Ages? Cornea, 32:496-502, 2012.
Meyer JJ, Meets H, et al, Mortality and Causes of Death Among Individuals With Keratoconus, Cornea, 2024 Apr 26.doi: 10.1097/ICO.0000000000003548. Online ahead of print