Refractive Changes during 72-hour Exposure to High Altitude after Refractive Surgery
| Autor: | Lawrence J. White, Thomas H. Mader, Vernon C. Parmley, Steven C. Schallhorn, John D. Ng, Kenneth C. Kubis, Benjamin N. Gilbert, Christopher L. Blanton |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
medicine.medical_specialty
Refractive error Intraocular pressure Keratometer business.industry medicine.medical_treatment Effects of high altitude on humans medicine.disease eye diseases Photorefractive keratectomy law.invention Ophthalmology Radial keratotomy law Refractive surgery medicine sense organs business Dioptre |
| Zdroj: | Ophthalmology. 103:1188-1195 |
| ISSN: | 0161-6420 |
| DOI: | 10.1016/s0161-6420(96)30523-x |
| Popis: | Purpose: The authors prospectively analyzed refractive and pachymetric parameters during exposure to high altitude after radial keratotomy (RK) and photorefractive keratectomy (PRK). Methods: The authors measured manifest and cycloplegic refraction, keratometry, computed video keratography, and central and peripheral pachymetry in six subjects who have undergone RK (11 eyes), six who have undergone PRK (12 eyes), and nine with myopia (17 eyes) at sea level and on three consecutive days at 14,100 feet. All measurements were repeated 1 week after subjects returned to sea level. Results: Subjects who have undergone RK demonstrated a significant and progressive increase in spherical equivalence (+0.30 ± 0.50 diopters on day 1 and +1.52 + 1.01 diopters on day 3; P P P P = 0.0006) by day 3 at high altitude. Refraction, keratometry, and pachymetry returned to baseline ( P = 1.000) after return to sea level. Conclusions: Seventy-two-hour exposure to high altitude in subjects who have had RK induces a significant, progressive, and reversible hyperopic shift in refraction with corresponding video keratographic and keratometric changes. The authors hypothesize that the high-altitude hypoxic environment causes increased corneal hydration in the area of the RK incisions, which may lead to central corneal flattening and a hyperopic shift in refractive error. Subjects who have had PRK and those with myopia are not susceptible to this refractive shift. The authors' RK data suggest that the time since surgery and the amount of surgery are related to the degree of hyperopic shift during altitude exposure. |
| Databáze: | OpenAIRE |
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