Mihai Pop

Functional outcome and satisfaction after photorefractive keratectomy: Part 2: survey of 690 patients

PURPOSEnTo document patient satisfaction and self-perceived quality of vision after bilateral photorefractive keratectomy (PRK).nnnDESIGNnNoncomparative, interventional case series.nnnPARTICIPANTSnConsecutive patients who underwent bilateral PRK from May 1994 through May 1997 by the 12 surgeons of four collaborating centers with a minimum of 4 months since the last surgery and up to 30 months since the first surgery.nnnMETHODSnA questionnaire with known psychometric properties was self-administered by the patients.nnnMAIN OUTCOME MEASURESnResponses to individual questions and scale scores.nnnRESULTSnA total of 929 questionnaires were sent, of which 690 were answered and returned (74.3% response rate). The preoperative spherical equivalent ranged from -0.38 diopters [D] to -27.75 D (mean, -5.32 D; standard deviation, 2.85 D). Although 91.8% of the patients were satisfied or very satisfied with their surgery, 96.3% considered that their main goal had been reached, and 95.7% would still choose to have surgery if they had it to do over. The degree of satisfaction was proportional to the postoperative uncorrected visual acuity in the best eye expressed in LogMAR (r = -0.18, P: = 0. 0001) and was negatively correlated with the importance of the corneal haze (r = -0.23, P = 0.0001). Daytime glare was reported to be greater than before surgery by 55.1% of patients. A decrease in night vision was reported by 31.7% of patients, and 31.1% of patients reported increased difficulty driving at night because of their vision.nnnCONCLUSIONSnOverall satisfaction after PRK for low to severe myopia appears to be very good. Glare and night vision disturbance, particularly bothersome for night driving, seem to constitute significant secondary effects that deserve further investigation and should be kept in mind for future improvements in the technique.

Photorefractive keratectomy versus laser in situ keratomileusis: A control-matched study

OBJECTIVEnPhotorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) outcomes were compared at 1, 3, 6, and 12 months after surgery.nnnDESIGNnRetrospective, nonrandomized, comparative study.nnnPARTICIPANTSnOne hundred seven LASIK-treated eyes (58 patients) and 107 PRK-treated eyes (91 patients) having myopia between -1 and -9.50 diopters (D). All LASIK-treated eyes were analyzed retrospectively and matched with PRK-treated eyes having sphere within +/-0.25 D, +/-1 D of cylinder, and +/-7 years of age.nnnINTERVENTIONnFor PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, (Nidek Co. Tokyo, Japan)nnnMAIN OUTCOME MEASURESnManifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, halos, and keratometry were evaluated before surgery and up to 12 months after surgery.nnnRESULTSnSeventy percent of eyes were evaluated at the 12-month postoperative exam. Of these eyes, 83% of LASIK cases and 86% of PRK cases had uncorrected visual acuities of 20/20 or better. Refractions within +/-0.5 D represented 78% of the LASIK eyes and 83% of the PRK eyes at that follow-up. Patients who underwent LASIK reported halos twice as often as patients who underwent PRK using a subjective scale. The odds ratio of high halos for LASIK versus PRK was 3.50 (95% confidence interval, 1.89-6.46; P<0.0001). At 1 month after surgery, 64% of the LASIK eyes were within +/-0.50 D compared with 77% of the PRK eyes. No eye lost 2 Snellen lines of best corrected visual acuity at 6 or 12 months after surgery. Ten PRK eyes (9.3%) and three LASIK eyes (2.8%) were retreated.nnnCONCLUSIONSnPRK and LASIK achieved equal refractive outcomes at all postoperative follow-ups, but LASIK patients were twice as likely to experience halos.

Predicting sulcus size using ocular measurements

Purpose: To predict sulcus size using ocular measurements. Setting: Michel Pop Clinics, Montreal, Quebec, Canada. Methods: Forty‐three eyes were evaluated using several techniques. Ultrasound biomicroscopy (UBM) echograms were taken to measure the anterior chamber depth (ACD), sulcus size, and central corneal thickness. The limbus size was measured with a caliper. Axial length, ACD, and pachymetry were measured by contact ultrasonography. Refraction and corneal power were also evaluated. Results: The coefficient of linear regression was 0.05 between the limbus and the sulcus size (P = .78), 0.76 between ultrasonography and UBM ACD measurements (P < .001), and 0.69 between ultrasonography and UBM pachymetry (P < .001). Paired t tests showed that ultrasound and UBM ACD measurements were not statistically different (P = .70) but that ultrasound and UBM pachymetry measurements were (P < .001). The sulcus versus limbus difference was 0.6 mm for myopia and 0.3 mm for hyperopia. A backward elimination multiple regression performed with all measures to predict sulcus size resulted in the following formula: Sulcus size = 18.9 − 0.023 × sphere + 0.15 × mean keratometry (R = 0.49; P = .005; statistical power = 0.89; standard error of estimate = 0.5 mm). Conclusion: Traditional estimation of sulcus size through limbal measurement is inadequate because limbus size alone cannot predict sulcus size. A general formula using the sphere and the mean corneal power can help predict sulcus size. Corneal power was significantly and negatively correlated with sulcus and limbus size as well as sphere. The standard error of sulcus measurement by UBM was 0.4 mm.

Multizone/multipass photorefractive keratectomy: Six month results

Abstract A multizone/multipass photorefractive keratectomy (MP‐PRK) technique was used to treat 315 eyes with the 193 nm VISX 20/20 excimer laser. Algorithms were developed to treat the full range of myopia, including 170 low myopic eyes (−1.0 to −6.0 diopters [D]), 105 moderately myopic eyes (−6.0 to −10.0 D), and 40 highly myopic eyes (‐10.0 to ‐27.0 D). Preoperative mean myopia was ‐6.69 D; astigmatism equal to or greater than −0.5 D (mean −1.18 D) was present in 193 eyes. At one month postoperatively, most eyes were slightly hyperopic (mean +0.8 D); this regressed to a mean of −0.16 D. At six months, 95.5% of low myopes, 84.8% of moderate myopes, and 59.5% of high myopes were within 1.0 D of emmetropia; 78.4% of high myopes were within 2.0 D of the intended correction. There was no loss of 20/40 best corrected visual acuity (BCVA) at six months; a significant gain in 20/25 BCVA was seen in the moderate and high myopia groups (P < .05). At six months, uncorrected visual acuity was 20/25 in 89.4% of low myopes, 75.0% of moderate myopes, and 25.7% of high myopes. Mean haze value was 0.48 at one month and was not significantly different among the three groups (0.44, 0.52, 0.51, respectively). A control group treated with the one‐pass multizone technique had a significantly higher amount of haze: 1.05 (P < .01). The data presented compare favorably with those obtained from other centers. Based on these results, we believe that MP‐PRK is a safe, reliable technique to correct most low, moderate, and high myopia.

Comparison of the pupil card and pupillometer in measuring pupil size

Purpose: To determine the difference in pupil size measured with the Colvard pupillometer in mesopic and scotopic luminance and with the Rosenbaum pupil card in mesopic luminance between 2 examiners. Setting: Michel Pop Clinics, Montreal, Quebec, Canada. Methods: Two examiners used the Colvard pupillometer and the Rosenbaum card to measure pupil size in 58 eyes. The Colvard pupillometer was used in mesopic and scotopic light conditions. The Rosenbaum card was used in mesopic luminance only. Pupil size was evaluated with a 1.0 mm interval scale at the nearest half millimeter. Results: For the 3 sets of data, the limits of agreement and coefficient of interrater repeatability were calculated and a 2 × 2 factorial analysis of variance was performed. Because of interexaminer bias, measurements done in mesopic luminance with the Rosenbaum card were not statistically different from those with the Colvard pupillometer in scotopic luminance, although interrater repeatability of the Colvard pupillometer (0.8 mm) was superior to that of the Rosenbaum card (1.3 mm). Conclusions: Examiner bias was the greatest statistical bias in all sets of measures. Surgeons may want to opt for a “safe” limit of pupil size (ie, 0.5 to 0.8 mm greater than the measured size) when calculating optical zones in refractive surgery. Future devices for pupil measurement should be based on automatic adjustment sizing.

Photorefractive keratectomy retreatments for regression. One-year follow-up.

PURPOSEnNinety eyes were retreated to correct myopic regression, with or without corneal haze, after primary photorefractive keratectomy (PRK); astigmatism ranging from -0.50 to -3 diopters (D) was present in 43 eyes.nnnRESULTSnThe sphere (mean +/- standard deviation) was -2.82 +/- 1.74 D before repeat surgery. At 6 months, the mean was +0.30 D; at 1 year, it was -0.17 D. Patients were divided into two groups: group 1 included 56 eyes with little or no haze (< or = 1). The mean sphere value for this group was -2.13 D before retreatment; at 1 year, it was -0.20 +/- 0.76 D. At 6 months, 84% of sphere values were within +/- 1 D of the intended correction, with a mean haze value of less than 0.5, similar to that before repeat surgery; there was a mean gain of 0.25 Snellen line of best-corrected visual acuity. Astigmatism equal or greater than -0.5 D was present in 34 eyes (mean, -1.17 +/- 0.55 D). At 6 months, astigmatism was reduced to -0.45 +/- 0.48 D. The second group included 34 eyes with corneal haze greater than 1 (mean, 2.7). The mean sphere value was -3.95 D before photorefractive keratectomy and -0.12 +/- 1.48 D 1 year after treatment. Fifty percent of the mean sphere values were within +/- 1 D at 6 months, with a mean haze value of 1. The gain in mean best-corrected visual acuity was 1.3 Snellen lines. The mean astigmatism in nine eyes was -1.75 +/- 0.75 D before photorefractive keratectomy and -0.72 +/- 0.78 D 6 months after treatment.nnnCONCLUSIONnThere is a significant difference in the outcome predictability between the two groups. A second photorefractive keratectomy can be done 6 months after the primary treatment in patients with regression with or without trace haze. This group has a High predictability in achieving a good correction, with a low complication rate. When haze is present, retreatments are less predictable with 40% of patients overcorrected. Generally, however, these eyes have a statistically significant decrease in haze (Students t test; P < 0.01) and an improvement in best-corrected visual acuity.

Clear lens extraction with intraocular lens followed by photorefractive keratectomy or laser in situ keratomileusis

OBJECTIVEnTo study photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) after clear lens extraction (CLE) with intraocular lens (IOL) implantation for hyperopia or astigmatism.nnnDESIGNnRetrospective, noncomparative interventional case series.nnnPARTICIPANTSnSixty-five eyes (55 subjects) had CLE with posterior chamber IOL implants for hyperopia up to 12.25 diopters (D); 31 eyes were retreated with PRK, and 34 eyes were retreated with LASIK for residual ametropias.nnnINTERVENTIONnFor PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, Nidek Co., Tokyo, Japan.nnnMAIN OUTCOME MEASURESnManifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, and halos were evaluated before surgery and at 1, 3, 6, and 12 months postoperative.nnnRESULTSnForty-seven eyes were evaluated at the 12-month postoperative examination: 96% of these eyes had spherical equivalents (SE) within +/-2 D of emmetropia, 79% of eyes had SE within +/-1 D of emmetropia and 51% of eyes had SE within +/-0.50 D of emmetropia. Eighty-five percent of the eyes at 12 months postoperative had uncorrected visual acuity of 20/40 or better, and 46% of eyes had uncorrected visual acuity of 20/20 or better. Eighty-seven percent of the eyes at 12 months postoperative had uncorrected visual acuity within 1 Snellen line of their initial best spectacle-corrected visual acuity (BSCVA) before all treatment. No eye lost 2 Snellen lines of BSCVA at 3, 6, or 12 months after PRK or after LASIK.nnnCONCLUSIONSnIOL implantation for CLE, although an invasive technique, resulted in better refractive outcomes without laser-related clinical complications after PRK or LASIK adjustment.

Refractive lens exchange versus iris-claw Artisan phakic intraocular lens for hyperopia

PURPOSEnTo study a paired-match comparison between refractive lens exchange with pseudophakic IOL implant (RLE) and Artisan phakic IOL for high hyperopia.nnnMETHODSnNineteen eyes (12 patients, 20 to 41 years old) with an Artisan phakic IOL (Model 203: 1.00-D increment) for hyperopia from +2.75 to +9.25 D were matched to 19 eyes (15 patients, 26 to 46 yr) with hyperopia from +2.75 to +7.50 D, who had refractive lens exchange (pseudophakic IOL implantation; lenses: 0.50-D increment). Average paired-match difference was 1.13 D and 7.7 years of age.nnnRESULTSnAt 1 month after surgery, 84% of refractive lens exchange/pseudophakic IOL eyes and 94% of Artisan phakic IOL eyes had a spherical equivalent refraction within +/- 1.00 D of emmetropia; 58% and 68% of eyes, respectively, were within +/- 0.50 D (P = .97). No eye lost lines of best spectacle-corrected visual acuity (BSCVA) and no significant changes in BSCVA were found in any eye at 1 month after surgery (P = .17). The percentage of eyes with uncorrected visual acuity (UCVA) of 20/40 or better improved from 79% to 89% of eyes at 1 to 2 months after phakic IOL; it remained at 89% to 82% of eyes from 1 to 2 months after refractive lens exchange/ pseudophakic IOL. The coefficient of correlation showed statistically better accuracy (intended vs. achieved refraction; P = .035) for the Artisan phakic IOL (R = 0.83) than for refractive lens exchange/ pseudophakic IOL (R = 0.50).nnnCONCLUSIONSnSpherical equivalent refraction outcome and BSCVA after surgery were similar for both procedures. The Artisan phakic IOL in carefully selected patients provided a better overall outcome for young patients with high hyperopia whose accommodation was preserved, as compared to refractive lens exchange.

Ultrasound biomicroscopy of the Artisan phakic intraocular lens in hyperopic eyes

Purpose: To study in situ the intraocular position of the Artisan iris‐claw intraocular lens (IOL) (model 203) (Ophtec) in phakic hyperopic eyes using ultrasound biomicroscopy (UBM). Methods: Echograms of the anterior chamber were taken preoperatively and 24 to 317 days postoperatively in 4 eyes implanted with the Artisan IOL (power +4.0 to +6.0 diopters). The preoperative anterior chamber depth (ACD) and the postoperative distance between the IOL and the corneal endothelium (endothelium−optic distance) and between the IOL and the lens were measured. The echograms were assessed for the effect of the IOL on iris tissue. Results: The preoperative ACD ranged from 3.10 to 3.56 mm and the postoperative endothelium−optic distance, from 2.03 to 2.54 mm. The distance between the lens and the posterior surface of the IOL ranged from 0.35 to 0.79 mm. Several UBM echograms showed indentation of iris tissue by the IOL haptics and optic edge, although no pigmentary dispersion was noted. Conclusions: Adequate space was maintained between the Artisan hyperopic IOL and the corneal endothelium, angle, and crystalline lens. Haptic indentation of the iris, which could lead to pigment erosion, was observed. Preoperative gonioscopy and maintenance of normal intraocular pressure postoperatively suggest the indentation was secondary to inadequate lens vaulting relative to the high natural arch of the iris in hyperopic eyes. Shortening the haptics or increasing the lens vault might resolve this problem.

Clear lens extraction with intraocular lens followed by photorefractive keratectomy or laser in situ keratomileusis1Historical image

OBJECTIVEnTo study photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) after clear lens extraction (CLE) with intraocular lens (IOL) implantation for hyperopia or astigmatism.nnnDESIGNnRetrospective, noncomparative interventional case series.nnnPARTICIPANTSnSixty-five eyes (55 subjects) had CLE with posterior chamber IOL implants for hyperopia up to 12.25 diopters (D); 31 eyes were retreated with PRK, and 34 eyes were retreated with LASIK for residual ametropias.nnnINTERVENTIONnFor PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, Nidek Co., Tokyo, Japan.nnnMAIN OUTCOME MEASURESnManifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, and halos were evaluated before surgery and at 1, 3, 6, and 12 months postoperative.nnnRESULTSnForty-seven eyes were evaluated at the 12-month postoperative examination: 96% of these eyes had spherical equivalents (SE) within +/-2 D of emmetropia, 79% of eyes had SE within +/-1 D of emmetropia and 51% of eyes had SE within +/-0.50 D of emmetropia. Eighty-five percent of the eyes at 12 months postoperative had uncorrected visual acuity of 20/40 or better, and 46% of eyes had uncorrected visual acuity of 20/20 or better. Eighty-seven percent of the eyes at 12 months postoperative had uncorrected visual acuity within 1 Snellen line of their initial best spectacle-corrected visual acuity (BSCVA) before all treatment. No eye lost 2 Snellen lines of BSCVA at 3, 6, or 12 months after PRK or after LASIK.nnnCONCLUSIONSnIOL implantation for CLE, although an invasive technique, resulted in better refractive outcomes without laser-related clinical complications after PRK or LASIK adjustment.