Optical analysis of visual improvement after correction of anisometropic amblyopia with a phakic intraocular lens in adult patients.
OBJECTIVE
To analyze possible reasons for an increase in visual acuity observed in myopic patients with anisometropic amblyopia after implantation of a phakic intraocular lens (PIOL) using a theoretical eye model.


METHODS
Retrospective case series.


METHODS
Fifty-nine eyes of 48 patients with anisometropic amblyopia implanted with an angle-supported PIOL.


METHODS
Inclusion criteria were anisometropia of at least 3 diopters (D) and a best spectacle-corrected visual acuity (BSCVA) of 0.7 or less in the best eye. Follow-up was performed at 1, 3, 6, and 12 months and then annually for up to 10 years. The theoretical analysis of mechanisms to explain the visual improvement was performed using a theoretical eye, based on the Kooijman model, in which the measured values of radii and thickness of the different surfaces were substituted. The magnification and spot size were calculated by a ray tracing process.


METHODS
Uncorrected visual acuity, improvement in best spectacle-corrected visual acuity, and spherical equivalent.


RESULTS
Mean gain in visual acuity was 3 lines (range, 0-7 lines). Fifty-four eyes (91.5%) gained at least 1 line of visual acuity, whereas no eyes lost lines of vision. The change in BSCVA did not correlate with preoperative BSCVA (Pearson coefficient, r = 0.19) or with the degree of anisometropia (Pearson coefficient, r = 0.23). The calculations using a Kooijman eye model corrected with spectacles and with a PIOL accounted for the full increase in visual acuity in terms of the magnification (increased by a factor of 1.2) and the spot size (reduced by a factor of 2).


CONCLUSIONS
After implantation of a PIOL, the visual acuity of myopic patients with anisometropic amblyopia showed a significant increase. This increase was explained using a theoretical eye model not only in terms of magnification but also including changes in aberrations. An evident role of neuroprocessing in this visual improvement was not identified.
Alió
Jorge L
JL
Department of Refractive Surgery, Instituto Oftalmológico de Alicante, Vissum Corporation, Alicante, Spain. rdioa@vissum.com
Ortiz
Dolores
D
Abdelrahman
Ayman
A
de Luca
Anel
A
D000328:Adult; D000550:Amblyopia / Q000503:physiopathology / Q000601:surgery*; D015858:Anisometropia / Q000503:physiopathology / Q000601:surgery*; D000867:Anterior Chamber / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019654:Lens Implantation, Intraocular; D007908:Lens, Crystalline / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D008962:Models, Theoretical; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology*