Evidence for delayed presbyopia after photorefractive keratectomy for myopia.

PURPOSE To evaluate uncorrected near visual acuity (NVA), accommodation, corneal aberrations, and the optical quality of the retinal image in presbyopic eyes after photorefractive keratectomy (PRK). DESIGN Nonrandomized comparative retrospective study. PARTICIPANTS Ten post-PRK patients and 10 normal patients. METHODS Twenty eyes (10 right and 10 left after PRK for myopia, minimum of 10 years after the operation; group A) were compared with 20 eyes (10 right and 10 left age- and gender-matched normal controls; group B). All subjects were over 40 years of age. MAIN OUTCOME MEASURES With best distance correction, NVA was measured at 40 cm (Jaeger, J series), and the range of accommodation (diopters [D]) was measured subjectively (negative relative amplitude and positive relative amplitude). The modulation transfer function (MTF) and corneal aberrations such as comalike, spherical (SAs), and higher order (HOAs) were measured with a Hartmann-Shack aberrometer. From the MTF curves, the spatial frequencies corresponding to contrast values of 0.1 and 0.5 were noted. RESULTS Mean ages (+/- standard deviations [SDs]) were 46.3 years (4.7) for group A and 47.6 years (4.9) for group B (P>0.05). Near acuity was J1 or better in 12 of 20 post-PRK and 4 of 20 control eyes. Mean accommodations (+/- SDs) were 3.2 D (1.14) for right group A eyes and 2.1 D (0.94) for right group B eyes (P = 0.0152), and 3.4 D (0.99) for left A eyes and 2.3 D (1.02) for left B eyes (P = 0.0168). Total HOA indexes (+/- SDs) were 1.449 (0.409) for right group A eyes and 0.824 (0.241) for right group B eyes (P = 0.008), and 1.464 (0.388) for left A eyes and 1.067 (0.542) for left B eyes (P = 0.0752). Pooling the data from post-PRK and control eyes, a significant correlation was found between near acuity and SA (right eyes, r = -0.535, P = 0.015; left eyes, r = -0.493, P = 0.027). Significant associations were found between accommodation, near acuity, HOA, and comalike aberration for right eyes only. Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.1 for right and left eyes were 14.96 (5.71) for right group A eyes and 22.02 (6.85) for right group B eyes (P = 0.074), and 15.11 (7.80) for left A eyes and 21.41 (9.00) for left B eyes (P = 0.271). Mean spatial frequencies (+/- SDs) corresponding to contrast values of 0.5 for right and left eyes were 2.86 (0.63) for right group A eyes and 3.21 (0.35) for right group B eyes (P = 0.596), and 2.76 (0.98) for left A eyes and 3.22 (0.27) for left B eyes (P = 0.194). CONCLUSIONS Compared with normal eyes, in previously myopic eyes treated with first-generation PRK lasers there is a tendency for (1) the optical quality of the retinal image to be reduced at low contrast, (2) the aberrations attributed to the corneal surface to increase, and (3) both measured subjective accommodation and near acuity to be greater than expected. We postulate that the corneal aberrations induced by PRK for myopia may reduce the quality of the retinal image for distance but enhance near acuity by way of a multifocal effect that can delay the onset of age-related near vision symptoms.

[1]  J. Garbus,et al.  Topographic analysis and visual acuity after radial keratotomy. , 1988, American journal of ophthalmology.

[2]  R A Weale,et al.  Human ocular aging and ambient temperature. , 1981, The British journal of ophthalmology.

[3]  J. Alió,et al.  Complications of photorefractive keratectomy for myopia: Two year follow‐up of 3000 cases , 1998, Journal of cataract and refractive surgery.

[4]  David A. Atchison,et al.  Optics of the Human Eye , 2023 .

[5]  J. C. Liu,et al.  Changes in corneal topography after excimer laser photorefractive keratectomy for myopia. , 1991, Ophthalmology.

[6]  J. Alió,et al.  Laser epithelium removal before photorefractive keratectomy. , 1993, Refractive & corneal surgery.

[7]  C. Munnerlyn,et al.  Photorefractive keratectomy: A technique for laser refractive surgery , 1988, Journal of cataract and refractive surgery.

[8]  J. F. Fleming.  Corneal Asphericity and Visual Function After Radial Keratotomy , 1993, Cornea.

[9]  D J Coleman,et al.  The shape of Bowman's layer in the human cornea. , 1998, Journal of refractive surgery.

[10]  S. Norrby,et al.  Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus , 2003, Journal of cataract and refractive surgery.

[11]  L J Maguire,et al.  A multifocal lens effect as a complication of radial keratotomy. , 1989, Refractive & corneal surgery.

[12]  D. Whitaker,et al.  Factors affecting light-adapted pupil size in normal human subjects. , 1994, Investigative ophthalmology & visual science.

[13]  D L Guyton,et al.  Optimal astigmatism to enhance depth of focus after cataract surgery. , 1991, Ophthalmology.

[14]  W. Charman,et al.  Postblink changes in total and corneal ocular aberrations. , 2004, Ophthalmology.

[15]  Robert Montés-Micó,et al.  Temporal changes in optical quality of air-tear film interface at anterior cornea after blink. , 2004, Investigative ophthalmology & visual science.

[16]  B. Gandevia,et al.  DECLARATION OF HELSINKI , 1964, Definitions.

[17]  H. Davson.  Physiology of the Eye , 1951 .

[18]  M Nakazawa,et al.  Apparent accommodation in pseudophakic eyes after implantation of posterior chamber intraocular lenses. , 1983, American journal of ophthalmology.

[19]  J. Marshall,et al.  The shape of the corneal apical zone after excimer photorefractive keratectomy , 1994, Acta ophthalmologica.

[20]  M. Netto,et al.  Pupil size in refractive surgery candidates. , 2004, Journal of refractive surgery.

[21]  S D Klyce,et al.  Topographic analysis and visual acuity after radial keratotomy. , 1989, American journal of ophthalmology-glaucoma.

[22]  P. Hersh,et al.  Disparity between refractive error and visual acuity after photorefractive keratectomy: Multifocal corneal effects , 1997, Journal of cataract and refractive surgery.

[23]  Adrian Glasser,et al.  Accommodation measurements in a prepresbyopic and presbyopic population , 2004, Journal of cataract and refractive surgery.

[24]  M Nakazawa,et al.  Apparent accommodation in pseudophakic eyes after implantation of posterior chamber intraocular lenses: optical analysis. , 1984, Investigative ophthalmology & visual science.

[25]  M B Datiles,et al.  Low myopia with low astigmatic correction gives cataract surgery patients good depth of focus. , 1990, Ophthalmology.

[26]  Apparent accommodation and corneal wavefront aberration in pseudophakic eyes. , 2002, Investigative ophthalmology & visual science.

[27]  P Artal,et al.  Determination of the point-spread function of human eyes using a hybrid optical-digital method. , 1987, Journal of the Optical Society of America. A, Optics and image science.

[28]  T. Oshika,et al.  Relationship between apparent accomodation and corneal multifocality in pseudophakic eyes. , 1999, Ophthalmology.