Excimer laser photorefractive keratectomy for myopia: six-month follow-up

Visual Functions After Photorefractive Keratectomy

1. 45 myopes (-3.0 to -6.0 D) were examined before and 1 and 6 months after photorefractive keratectomy (PRK). Visual acuity (VA) was tested using Snellen and logMAR charts. Contrast sensitivity (CS) was measured using a computerized system. 2. Preoperative best corrected VA (BCVA) in myopes was significantly lower in comparison with a control group using logMAR charts only. A reduction of BCVA by both methods at 1. month and its return after 6 months nearly to original values was noted. 3. Significantly lower values of CS were found in patients before PRK compared to the control group. After 1 and 6 months stayed the values on preoperative level.

Advances in refractive surgery: 1975 to the present

PURPOSE

To review the major advances in the field of refractive surgery occurring over the past 25 years.

METHODS

Literature review.

RESULTS

The major developments in refractive surgery over the past 25 years are reviewed.

CONCLUSIONS

The past 25 years have witnessed great changes in refractive surgery. As a result of advancements in technology, instrumentation, and technique, we have seen improvements in the treatment of all types of ametropias. In this article, we review some of the successes and failures of the past quarter-century.

Retreatment after photorefractive keratectomy for low myopia

OBJECTIVE

The purpose of the study was to evaluate the results of retreatment for low myopia after primary photorefractive keratectomy (PRK).

DESIGN

A prospective study.

PARTICIPANTS

A total of 48 eyes of 37 patients from 566 eyes of 331 patients originally treated for myopia of up to -6 diopters (D) were studied.

INTERVENTION

Photorefractive keratectomy by the Coherent Schwind Keratom II excimer laser was performed.

MAIN OUTCOME MEASURES

The parameters evaluated were visual acuity, refraction, and corneal clarity.

RESULTS

Of the 566 eyes with myopia up to -6 D, 48 eyes (8.5%) required retreatment. The sphere (mean +/- standard deviation) was -0.88 +/- 1.24 D before second surgery. At 6 months, the mean was -0.04 +/- 0.91; at 1 year, it was -0.33 +/- 0.75 D. At 6 months, 75% of sphere value was within +/- 1 D. The preoperative uncorrected visual acuity (UCVA) was 20/200 or worse in 12.8% of eyes and 20/40 or better in 40.4% of eyes. Six months after reoperation, 20/60 UCVA was obtained in 17.4% of eyes. All others (82.6%) had UCVA of 20/40 or better, 26.1% better than 20/20. The proportion of eyes with best spectacle-corrected visual acuity better than 20/20 decreased from 60.0% to 47.1% 6 months after reoperation. Six months after reoperation, haze 1 was present in 42.9% and haze 2 in 4.7% of eyes, and in no eye was haze worse.

CONCLUSION

Retreatment after PRK for low myopia can significantly increase UCVA and decrease residual refractive error without significant complications.

Permanent glaucomatous visual loss after photorefractive keratectomy

A 41-year-old man who had photorefractive keratectomy (PRK) for myopia developed corneal haze. After intensive treatment with topical corticosteroids, he developed elevated intraocular pressure and optic nerve damage. Because of an inadequate response to steroid discontinuation and medical treatment, the patient required a glaucoma filtering procedure. Corticosteroid-induced glaucoma is a possible complication of the treatment often associated with PRK. Careful patient screening and disclosure of this risk are imperative.

Removal of Corneal Epithelium with Phototherapeutic Technique during Multizone, Multipass Photorefractive Keratectomy

BACKGROUND

The therapeutic mode of the VISX 20/20 excimer laser was used to remove the corneal epithelium prior to performing photorefractive keratectomy (PRK) with a multizone, multipass technique.

METHODS

A retrospective analysis was performed of 120 eyes of 90 patients that were treated for preoperative spherical refractive errors from -1.00 to -7.00 diopters (D) (mean -3.90 D, SD 1.54) by one surgeon (DGJ) over 7 months.

RESULTS

Six-month follow-up was obtained in 76 eyes (63%). Sixty-nine eyes (91%) achieved a spherical equivalent refraction within +/-1.00 D of emmetropia. Regression of effect averaged -0.35 D (SD 0.53 D) from 1 to 6 months after surgery. Mean postoperative uncorrected visual acuity at 6 months was 20/25 (range 20/15 to 20/200). Seventy-three eyes (96%) achieved uncorrected visual acuity of 20/40 or better, 67 (88%) achieved uncorrected visual acuity of 20/25 or better, and 76 (71%) achieved 20/20 or better. Three eyes (4%) lost one line of spectacle-corrected visual acuity; no eye lost more than one line. There were no significant surgical complications.

CONCLUSION

Removal of corneal epithelium with the Summit Excimed UV 200 LA excimer laser using multizone, multipass photoablation yields visual and refractive results that compare favorably with published PRK series with excellent short-term stability.

Results of excimer laser retreatment of residual myopia after previous photorefractive keratectomy

BACKGROUND

Nine percent to 30% of all patients who undergo a single excimer laser photorefractive keratectomy (PRK) do not achieve an unaided visual acuity of 20/ 40 or better and may require optical correction to obtain adequate vision.

METHODS

The authors performed a retrospective analysis of the records of 164 patients who had undergone retreatment with the excimer laser for residual myopia after a previous PRK. Mean follow-up was 35.5 +/- 15.2 weeks (range, 26-104 weeks).

RESULTS

The mean spherical equivalent (MSE) before retreatment was -2.59 +/- 1.36 diopter (D) (range, -0.50 to -7.75 D). The final MSE after reablation was -0.52 +/- 1.36 D (range, 2.50 to -5.50). Of the 164 patients, 107 (65.2%) obtained a final refraction within 1.00 D of emmetropia and 111 (67.3%) achieved an unaided visual acuity of 20/40 or better. Only 10 patients (6.1%) lost more than one Snellen line of best-corrected visual acuity. The final MSE result for the subgroup of patients who had a pre-retreatment myopia of between -0.50 and -1.90 D (-0.31 +/- 1.09 D) was significantly closer to emmetropia than that of the subgroup with a residual myopia of -4.00 to -7.75 D (-1.62 +/- 1.94 D).

CONCLUSIONS

Excimer laser retreatment may provide a relatively safe and predictable method of correcting residual myopia after an earlier PRK with a 25% extra correction recommended for residual myopia.