Refractive changes during 72-hour exposure to high altitude after refractive surgery

T. H. Mader, C. L. Blanton, B. N. Gilbert, K. C. Kubis, S. C. Schallhorn, L. J. White, V. C. Parmley, John Ng

Research output: Contribution to journalArticle

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Abstract

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 <0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P <0.004; PRK, P <0.007; control subjects, 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.

Original languageEnglish (US)
Pages (from-to)1188-1195
Number of pages8
JournalOphthalmology
Volume103
Issue number8
StatePublished - 1996
Externally publishedYes

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Radial Keratotomy
Refractive Surgical Procedures
Photorefractive Keratectomy
Myopia
Oceans and Seas
Refractive Errors
Mydriatics
Healthy Volunteers

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Mader, T. H., Blanton, C. L., Gilbert, B. N., Kubis, K. C., Schallhorn, S. C., White, L. J., ... Ng, J. (1996). Refractive changes during 72-hour exposure to high altitude after refractive surgery. Ophthalmology, 103(8), 1188-1195.

Refractive changes during 72-hour exposure to high altitude after refractive surgery. / Mader, T. H.; Blanton, C. L.; Gilbert, B. N.; Kubis, K. C.; Schallhorn, S. C.; White, L. J.; Parmley, V. C.; Ng, John.

In: Ophthalmology, Vol. 103, No. 8, 1996, p. 1188-1195.

Research output: Contribution to journalArticle

Mader, TH, Blanton, CL, Gilbert, BN, Kubis, KC, Schallhorn, SC, White, LJ, Parmley, VC & Ng, J 1996, 'Refractive changes during 72-hour exposure to high altitude after refractive surgery', Ophthalmology, vol. 103, no. 8, pp. 1188-1195.
Mader TH, Blanton CL, Gilbert BN, Kubis KC, Schallhorn SC, White LJ et al. Refractive changes during 72-hour exposure to high altitude after refractive surgery. Ophthalmology. 1996;103(8):1188-1195.
Mader, T. H. ; Blanton, C. L. ; Gilbert, B. N. ; Kubis, K. C. ; Schallhorn, S. C. ; White, L. J. ; Parmley, V. C. ; Ng, John. / Refractive changes during 72-hour exposure to high altitude after refractive surgery. In: Ophthalmology. 1996 ; Vol. 103, No. 8. pp. 1188-1195.
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abstract = "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 <0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P <0.004; PRK, P <0.007; control subjects, 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.",
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T1 - Refractive changes during 72-hour exposure to high altitude after refractive surgery

AU - Mader, T. H.

AU - Blanton, C. L.

AU - Gilbert, B. N.

AU - Kubis, K. C.

AU - Schallhorn, S. C.

AU - White, L. J.

AU - Parmley, V. C.

AU - Ng, John

PY - 1996

Y1 - 1996

N2 - 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 <0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P <0.004; PRK, P <0.007; control subjects, 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.

AB - 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 <0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P <0.004; PRK, P <0.007; control subjects, 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.

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