Factors influencing the outcome of hyperopic lamellar keratoplasty.
OBJECTIVE
To determine which factors affect the refractive outcome of hyperopic lamellar keratoplasty.


METHODS
Jules Stein Eye Institute and Department of Ophthalmology, UCLA, Los Angeles, California, USA.


METHODS
This retrospective study comprised 38 consecutive eyes of 25 patients with naturally occurring hyperopia who had automated lamellar keratoplasty by one surgeon. Mean attempted correction was 3.80 diopters (D) (range of 1.50 to 6.00 D); 34 eyes were followed for 3 months. The effect of applanation lens diameter, keratometry, age, corneal thickness, absolute flap thickness in microns, thickness of the posterior lamellae in microns, and flap thickness as a percentage of corneal thickness were determined using multivariate linear regression.


RESULTS
With current nomograms, mean undercorrection 3 months after hyperopic lamellar keratoplasty was 1.26 D +/- 0.91 (SD); 14 of 34 eyes were within +/- 1.00 D of the attempted correction. The best predictive factors of achieved correction were applanation lens diameter and absolute flap thickness in microns, which accounted for 54% of the variability in outcome. Keratometry, corneal thickness, and flap thickness as a percentage of corneal thickness had no significant additional predictive value.


CONCLUSIONS
The refractive outcome of hyperopic lamellar keratoplasty was primarily determined by applanation lens diameter and absolute flap thickness in microns. Current nomograms suggest that flap thickness as a percentage of corneal thickness is a major determinant of effect, but this factor appears unimportant to the refractive effect of hyperopic lamellar keratoplasty. We hypothesize that it is slight swelling of the anterior corneal stroma rather than the bulging of the posterior cornea that causes the hyperopic correction in hyperopic lamellar keratoplasty.
Ghiselli
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Jules Stein Eye Institute, UCLA 90095-7003, USA.
Manche
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Maloney
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D000328:Adult; D000368:Aged; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D016039:Corneal Transplantation; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D007908:Lens, Crystalline / Q000502:physiology; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D013524:Surgical Flaps; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology