Evaluation of penetrating keratoplasty in keratoconus. Nine years follow-up

Penetrating keratoplasty was done in 104 cases with keratoconus. The donor material were preserved either as a whole eye in moist chamber at 4 degrees C, or as a corneoscleral segment in MK-medium at 4 degrees C, or in a tissue culture. The post-operative observation time varied between 6 months and 9 years. The visual acuity was found to be better than before surgery in 96%, unchanged in 3%, and worse in 1% of the cases. The average visual acuity was found to be after 6 months 0.25 +/- SD 0.2 and after 7 years 0.65 +/- SD 0.23. The post-operative spherical error of refraction was found to be -3.26 +/- SD 3.5 D, and the post-surgical astigmatism -2.6 +/- SD 1.9 D.     

Laser in situ keratomileusis for ametropia after penetrating keratoplasty

PURPOSE: To evaluate the efficacy of excimer laser in situ keratomileusis (LASIK) in the treatment of refractive errors after penetrating keratoplasty. METHODS: Eight eyes underwent LASIK after a mean 71 months (SD 60) following the initial penetrating keratoplasty. A full ophthalmic assessment was performed before LASIK and at 1 week, 1, 3, 6, and 12 months after surgery. Mean follow-up was 8.6 months (SD 3.2). RESULTS: No eyes lost any Snellen lines of best spectacle-corrected visual acuity at the latest follow-up. Mean reduction in spherical equivalent refraction was 91% from -6.79 D (SD 4.17) to -0.64 D (SD 1.92) and mean reduction of cylinder was 72% from -6.79 D (SD 3.28) to -1.93 D (SD 1.17) at 6 months. Mean surgically induced astigmatism was 5.50 D (SD 2.42) and the index of surgically induced astigmatism divided by the initial cylinder expressed as a percentage was 81%. Mean outcome indices were: correction index 0.87, index of success 0.31, and angle of error 0.95 degrees. Three eyes (43%) achieved a spherical equivalent refraction of +/-0.50 D and 4 eyes (57%) achieved a spherical equivalent refraction of +/-1.00 D of emmetropia. CONCLUSIONS: The efficacy of LASIK after penetrating keratoplasty was good compared to incisional or surface based excimer laser methods and has the advantage of reducing the myopic spherical equivalent refraction in addition to astigmatism, thus improving the uncorrected visual acuities.     

Conductive keratoplasty for low to moderate hyperopia: 1-year results

PURPOSE: To assess the safety, efficacy, and stability of conductive keratoplasty in the treatment of low to moderate hyperopia and evaluate the impact of the procedure on the quality of vision. METHODS: Thirty-six eyes (25 patients; 13 female and 12 male) were treated for hyperopia up to +3.25 D with a Refractec ViewPoint CK system and followed for 1 year. Mean age was 50.2 +/- 8.7 years (range 31 to 71). RESULTS: Before surgery, mean spherical equivalent refraction was +1.90 +/- 0.60 D (range +1.00 to +3.25 D), decreasing at 1 year after conductive keratoplasty to -0.06 +/- 0.80 D, and was within +/- 0.50 D of emmetropia in 68% (24 eyes) and within +/- 2.00 D in all eyes. Twelve months after conductive keratoplasty, uncorrected visual acuity was 20/20 or better in 19 eyes (50%) and 20/40 or better in 32 eyes (89%). No eye lost > or = 2 Snellen lines or had induced cylinder > or = 2.00 D. The mean root mean square values for higher order optical aberrations were 0.060 +/- 0.039 before and 0.174 +/- 0.170 at 3 months after surgery. No statistically significant changes in contrast sensitivity were noted. CONCLUSIONS: Conductive keratoplasty for low to moderate hyperopia provided safe, effective, and stable results both in refraction and quality of vision.     

Two-stage laser in situ keratomileusis to correct refractive errors after penetrating keratoplasty

PURPOSE: To evaluate the effect of a two-stage laser in situ keratomileusis (LASIK) procedure on eyes with high astigmatism and/or anisometropia after penetrating keratoplasty. METHODS: Eleven postoperative penetrating keratoplasty eyes were included in a prospective, non-controlled study. All patients had at least 4.00 D of astigmatism and/or at least 3.00 D of anisometropia and were spectacle and contact lens intolerant. Two-stage LASIK was performed; in the first stage a hinged corneal flap 160 microm in thickness and 9 mm in diameter was created. After stabilization of corneal shape (1 to 3 months after keratotomy), the corneal flap was lifted and laser refractive treatment (second stage) was performed. RESULTS: After the first stage, a statistically significant reduction in refractive astigmatism (P<.01) was recorded. In all eyes but one, best spectacle-corrected visual acuity was maintained or improved after the procedure. Three months after the second stage, refractive astigmatism in 8 of 11 eyes (73%) was within +/- 1.00 D, and spherical equivalent refraction in 9 of 11 eyes (82%) was within +/- 1.00 D of intended correction. Preoperative irregular astigmatism persisted in three patients (3 eyes) who could not be corrected within +/- 1.00 D of refractive astigmatism and/or +/- 1.00 D of intended spherical equivalent refraction. In one eye, an interface infiltrate developed shortly after creation of the flap, and resulted in limited melting. CONCLUSIONS: A two-stage LASIK procedure improved visual acuity and refraction in postoperative penetrating keratoplasty eyes with high astigmatism and/or anisometropia. Complications were uncommon but can lead to loss of vision.     

Artisan phakic iris claw intraocular lens for high primary and secondary hyperopia

PURPOSE: To evaluate the efficacy, predictability, and safety of the Artisan iris claw phakic intraocular lens for the correction of high primary and secondary hyperopia. METHODS: Fifty-seven eyes were divided into two groups: 29 eyes had primary hyperopia (mean refraction 6.06 +/- 1.26 D, and 28 eyes had secondary hyperopia, (mean refraction 5.88 +/- 1.88 D) induced or residual following a previous corneal refractive procedure. Consecutive implantation of the Artisan iris claw phakic intraocular lens was performed. Main outcome measures recorded were BSCVA, UCVA, refraction, and astigmatic change, intraocular inflammation, and endothelial cell loss. RESULTS: Primary hyperopic group: Preoperatively, mean UCVA was 0.4 +/- 0.7 and mean BSCVA was 0.2 +/- 0.6. After implantation, mean UCVA was 0.3 +/- 0.6 and BSCVA was 0.1 +/- 0.6. Mean cycloplegic residual spherical refractive error after surgery was 0.10 +/- 0.57 D (range -1 to +2 D). Mean surgically induced astigmatism was 1.48 +/- 0.89 D. Safety index was 1.11. Efficacy index was 0.83. Secondary hyperopic group: Preoperatively, mean UCVA was 0.5 +/- 0.7 and mean BSCVA was 0.2 +/- 0.6. Postoperatively, mean UCVA was 0.4 +/- 0.7 and mean BSCVA was 0.2 +/- 0.6. Mean cycloplegic residual spherical refractive error was 0.55 +/- 1.49 D. Mean surgically induced astigmatism was 1.85 +/- 1.19 D. Safety index was 1.05. Efficacy index was 0.7. Postoperative iridocyclitis was observed in one eye (3.4%) in the primary group and in three eyes (10.7%) in the secondary group. Overall corneal endothelial cell loss at 1 year of follow-up was 9.4%. CONCLUSION: The Artisan iris claw phakic intraocular lens was reasonably safe and predictable for correcting high hyperopia.     

Laser in situ keratomileusis to correct refractive errors after keratoplasty

PURPOSE: To assess the safety and effectiveness of excimer laser in situ keratomileusis (LASIK) to correct refractive myopia, astigmatism, or both after keratoplasty. SETTING: Eye Clinic Day Hospital, S?o Paulo, Brazil. METHODS: Twenty-two eyes that had previously had corneal transplantation were studied. Laser in situ keratomileusis was performed using the Chiron automated microkeratome and the VISX Twenty-Twenty B excimer laser. RESULTS: Mean follow-up after LASIK was 10.09 months +/- 3.87 (SD). The spherical equivalent refraction dropped from -4.55 +/- 3.66 D before LASIK to -0.67 +/- 1.24 D after surgery. At the last examination, 72.7% of patients had a refractive error within +/- 1.00 D of emmetropia and 54.5% had uncorrected visual acuity of 20/40 or better. Vector analysis of astigmatic correction showed an index of success of 54.0%. Best spectacle-corrected visual acuity was unchanged in 8 cases, improved in 9, and decreased in 5. Significant endothelial cell loss, keratoplasty wound dehiscence, and other serious complications did not develop in any eye. CONCLUSION: The correction of refractive error with LASIK in postkeratoplasty patients proved to be safe, effective, and predictable. Further studies with longer follow-up are needed to determine the method's clinical value.     

Laser in situ keratomileusis for correction of high astigmatism after penetrating keratoplasty

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) for correction of high astigmatism after penetrating keratoplasty, and to assess the refractive results and predictability of the procedure. METHODS: LASIK was performed on 19 patients (19 eyes) with high astigmatism after penetrating keratoplasty, using the Chiron Automated Corneal Shaper and the Chiron-Technolas Keracor 116 excimer laser. The amount of preoperative refractive astigmatism ranged from 6.50 to 14.50 D (mean, 9.21 +/- 1.95 D) and the spherical component of manifest refraction ranged from -7.00 to +1.25 D (mean, -2.14 +/- 2.11 D). All patients completed a minimum follow-up of 12 months. RESULTS: Refraction was stable after 3 months. At 1 year after LASIK, the amount of refractive astigmatism was reduced to a mean of 1.09 +/- 0.33 D (range, 0.50 to 1.75 D), with 57.9% of the eyes within +/- 1.00 D of refractive astigmatism. The mean percent reduction of astigmatism was 87.9 +/- 3.7%. The postoperative spherical component of manifest refraction ranged from -1.00 to +1.75 D with a mean of +0.43 +/- 0.82 D. Vector analysis showed that the mean amount of axis deviation was 1.1 +/- 1.3 degrees and the mean percent correction of preoperative astigmatism was 92.6 +/- 8.4%. There were no intraoperative complications. Spectacle-corrected visual acuity was not reduced in any eye, and improved by 2 or more lines in 42.1% of eyes after LASIK. CONCLUSION: LASIK with the Chiron-Technolas Keracor 116 excimer laser was effective for correction of both astigmatism and myopia after penetrating keratoplasty. The procedure proved to be safe and gave fairly predictable and stable refractive results.     

Long-term follow-up of ultrathin corneas after surface retreatment with phototherapeutic keratectomy

PURPOSE: To evaluate visual acuity and long-term stability after phototherapeutic keratectomy (PTK) in patients with corneal thickness less than 400 microm and cornea-related vision problems. SETTING: Department of Ophthalmology, Istituto Clinico Humanitas, Rozzano-Milan, Italy. METHODS: This retrospective study comprised 48 eyes that had PTK for complications after photorefractive keratectomy that removed more than 200 microm of tissue. Phototherapeutic keratectomy was performed with the Nidek EC-5000 excimer laser with 10 Hz frequency, intraoperative topography, and masking fluid over an ablation diameter of 10.0 mm. The follow-up was 5 years. The mean preoperative best spectacle-corrected visual acuity (BSCVA) was 0.2 +/- 0.09 (SD) with -2.53 +/- 2.34 diopters (D), and the mean pachymetry was 390 +/- 38 microm. The efficacy parameters were pachymetry and visual acuity at 1 year and the stability parameters, optical refraction, corneal curvature (calculated as the mean curvature over the entire 3.0 mm and 5.0 mm central zones), and pachymetry from 1 to 5 years. RESULTS: At 1 year, the mean BSCVA was 0.6 +/- 0.72 with -2.15 +/- 1.67 D and the mean pachymetry, 341 +/- 40 microm. At 5 years, the mean BSCVA was 0.7 +/- 0.15 with -2.33 +/- 1.12 D and the mean pachymetry, 339 +/- 48 microm. In all patients, there was an improvement of 4 or more Snellen lines. Statistical evaluation of refraction and corneal curvature values at 1 and 5 years indicated no statistically significant differences. CONCLUSIONS: After PTK in eyes with ultrathin corneas, there was significant improvement in BSCVA and long-term stability of the optical refraction, corneal curvature, and pachymetry. In selected cases, 10.0 mm ablation zone PTK may be an alternative to penetrating keratoplasty, offering long-term corneal stability.     

Prediction of postoperative refraction using intraoperative retinoscopy]

PURPOSE: Postoperative refraction was calculated using aphakic refraction measured with intraoperative retinoscopy, and its clinical usefulness was investigated statistically. OBJECTS AND METHODS: We studied 115 eyes of 89 patients, 28 males and 61 females aged 35 to 90 years, who had received intracapsular insertion of an intraocular lens. To decrease the error in measuring, retinoscopy was performed after the attachment of a hard contact lens of +15 D to the patient's cornea, with the exclusion of high myopia. We modified the Haigis calculation and used it to predict the postoperative refraction. RESULTS: The refraction could be measured in 112 eyes. The mean error between the actual and the predicted (actual minus predicted) in 112 eyes was 0.40 +/- 1.05 (mean +/- standard deviation) D. The mean error calculated using the SRK-II method, the Binkhorst method, and the Holladay method was -0.09 +/- 1.13 D, -0.58 +/- 1.00 D, and -0.44 +/- 1.00 D, respectively. The mean error of the average of these three formulas and our method was 0.15 +/- 0.82 D, -0.09 +/- 0.83 D, and -0.02 +/- 0.82 D, respectively. CONCLUSION: Our method seemed to have the same accuracy as other calculation formulas. By using our method together with other formulas, the postoperative refraction could be predicted more accurately.     

Refractive error in premature infants

PURPOSE: To determine the incidence and the degree of refractive error between the ages of 2 weeks and 6 months in premature infants without retinopathy of prematurity and to seek a correlation between refractive error and age at examination, birth weight, or gestational age. SUBJECTS AND METHODS: In this observational cross-sectional study, eye refraction in 390 premature infants, with no ocular pathology, was measured by cycloplegic retinoscopy at the age of 2 weeks to 6 months. A correlation was sought between refractive error and perinatal variables. RESULTS: Of the 390 infants reviewed, 347 (89%) had a refractive error and 43 (11%) were emmetropic in both eyes. Most of the infants were hyperopic (76.8%). Myopia was observed in only 11.9%. Astigmatism was found in 24.4% of the infants. The mean age at examination was 2.1 +/- 1 months; the mean birth weight was 1639 +/- 444 g, and the mean gestational age at birth was 32.2 +/- 2.4 weeks. The mean spherical equivalent of refraction was +1.56 +/- 1.82 diopters (D) in the right eye and +1.55 +/- 1.78 D in the left eye. Refractive error was positively correlated with age at examination ( R = 0.16, P = 0.001). The mean refractive error was +1.24 D in infants aged 1 month or less and reached +2.50 D at the age of 4 to 6 months. Refractive error was not correlated with birth weight or gestational age. CONCLUSIONS: The incidence of refractive error in premature infants without retinopathy of prematurity in the first 6 months of life may be as high as 89%. Most of these infants are hyperopic. Eye refraction is correlated with age at examination, but not with birth weight or gestational age.     

Penetrating keratoplasty for corneal ectasia after laser in situ keratomileusis

PURPOSE: To improve the visual acuity of patients with progressive keratectasia following laser in situ keratomileusis (LASIK). METHODS: Five eyes of four patients underwent penetrating keratoplasty for ectasia after LASIK: In one patient the second eye was operated on 10 months after the first keratoplasty. The pre- and postoperative refraction, best spectacle-corrected visual acuity, and topographic data were evaluated. RESULTS: The preoperative refraction was -20.0 diopters (D) with high cylindrical values in all eyes at the time of surgery. After penetrating keratoplasty, mean spherical equivalent was -13.08+/-3.62 (SD) and mean refractive cylinder was -3.87+/-1.12 (SD). In one eye Urrets-Zavalia syndrome was noted as an early postoperative complication. In the second operated eye of another patient, there had been graft rejection several times. In this patient, frequent steroid use led to secondary glaucoma and he required filtering surgery. CONCLUSIONS: Penetrating keratoplasty is effective and successful in treating iatrogenic keratectasia after LASIK, but these patients need a close and lifelong follow-up to treat lateterm complications such as graft rejection and secondary glaucoma.     

Videokeratography in conductive keratoplasty

PURPOSE: We used EyeSys videokeratography to evaluate corneal shape changes induced by conductive keratoplasty, a procedure that utilizes radio frequency energy to alter corneal shape to correct hyperopia. METHODS: Follow-up data were available for 19 eyes (out of 24 eyes of 13 patients). Preoperative spherical hyperopia ranged from +0.75 to +3.25 D with astigmatism <0.75 D. Manifest refractive spherical equivalent refraction (MRSE), uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), topographical parameter predicted corneal acuity (PCA), corneal uniformity index (CU Index), regular astigmatism, total astigmatism, average simulated keratometry (Avg Sim K), effective refractive power, and asphericity were measured preoperatively and at 6 and 12 months postoperatively. RESULTS: Twelve months postoperatively, mean PCA, CU Index, and BSCVA were maintained at preoperative levels. Mean UCVA (LogMAR) improved from 0.53+/-0.21 to 0.10+/-0.19 (P<.05) with a mean MRSE change from +1.62+/-0.76 D to -0.06+/-0.84 D (P<.05) from preoperative to 12 months postoperative. Mean asphericity increased +0.044+/-0.24 D (P>.05), mean Avg Sim K increased 1.88+/-0.72 D (P<.05), mean effective refractive power increased 1.71+/-0.79 D (P<.05), mean cylinder (cycloplegic refraction) increased 0.19+/-0.36 D (P<.05), mean regular astigmatism increased 0.25+/-0.49 D (P>.05), and mean irregular astigmatism decreased 0.01+/-0.13 D (P>.05) from preoperative to 12 months after conductive keratoplasty. CONCLUSIONS: Avg Sim K and effective refractive power changes support the refractive results; 12-month postoperative maintenance of BSCVA, PCA, and CU Index suggest the procedure is safe. Conductive keratoplasty induced a slight regular astigmatism in some eyes, which decreased with time. The increase in mean corneal asphericity indicated possible induction of central and peripheral cornea changes.     

Accuracy of intraocular lens power estimation in eyes having phacovitrectomy for macular holes

PURPOSE: To report the accuracy of intraocular lens (IOL) power estimation in eyes having combined phacoemulsification and vitrectomy for macular holes and to compare the axial length (AL) in those eyes with that in the fellow eyes. SETTING: Calderdale Royal Hospital, Halifax, West Yorkshire, United Kingdom. METHOD: The mean and standard deviation of the refractive aim, achieved refraction, and postoperative prediction error (calculated as difference between achieved refraction and refractive aim) were determined in 40 patients who had phacovitrectomy with gas tamponade for the treatment of idiopathic macular holes. The percentage of patients with an achieved refraction within +/-0.50 diopter (D), +/-1.00 D, and more than 2.00 D of the refractive aim was recorded. The mean absolute error (MAE) of the postoperative prediction error was calculated. In addition, the AL in eyes with macular holes was compared with that in fellow eyes. Axial lengths were measured using applanation A-scan ultrasound. RESULTS: Of eyes having phacovitrectomy, 45.0%, 67.5%, and 90.0% achieved a postoperative refraction within +/-0.50 D, +/-1.00 D, and +/-2.00 D, respectively, of the refractive aim; 10.0% of eyes were more than -2.00 D from the refractive aim. The overall postoperative prediction error ranged from +1.64 D to -2.51 D. The mean refractive aim was +0.30 +/- 0.72 D and the mean achieved refraction, -0.09 +/-1.25 D. There was no clinically significant difference between the means. The mean postoperative prediction error was -0.39 +/- 1.01 D, suggesting a myopic overcorrection occurred postoperatively. The MAE of the postoperative prediction error was 0.83 D. The mean AL was 23.40 mm in operated eyes and 23.46 mm in fellow eyes. CONCLUSIONS: The achieved refraction after phacovitrectomy for macular holes was comparable to results after phacoemulsification alone. The myopic overcorrection after phacovitrectomy might be a result of the gas bubble causing forward displacement of the capsular bag and IOL or inaccuracies in AL and keratometry measurements. Aiming for residual hyperopia may counteract the overcorrection. There was no difference in AL between eyes with macular holes and fellow eyes.     

Non-contact holmium:YAG laser thermal keratoplasty for hyperopia: two-year follow-up

PURPOSE: We evaluated the safety and efficacy of the non-contact holmium:YAG laser thermal keratoplasty (LTK) for the treatment of mild to moderate hyperopia without astigmatism. METHODS: A prospective, non-comparative case series included 50 eyes of 28 patients (aged > or =40 years) who had stable refraction and an astigmatic component < +0.50 diopters (D). We applied the non-contact pulsed holmium:YAG laser to treat the hyperopic spherical component using the Hyperion LTK System. All patients had minimum 12-month follow-up and 64% (18 patients) had 24-month follow-up. RESULTS: The mean age of patients was 48.4 +/- 8.23 years (range: 40 to 62 years). The preoperative hyperopic mean spherical equivalent refraction was +2.32 +/- 0.975 D (range: +1.00 to +4.75 D). Postoperatively, the subjective manifest refraction decreased from the preoperative mean value of +2.32 D to a mean -0.09 D at 1 month after surgery and regressed to +0.315 D at the last follow-up examination, resulting in a mean correction of +2.005 +/- 0.81 D at 24 months after surgery. Preoperatively, mean uncorrected visual acuity in LogMAR units was 0.798 +/- 0.353 and at 12 months after surgery, it was a mean 0.108 +/- 0.136. Keratometric power increased from 42.595 +/- 1.949 D before surgery to 44.605 +/- 1.626 D at 24 months after surgery. CONCLUSIONS: Holmium:YAG LTK was an acceptable alternative for the correction of mild to moderate hyperopia in this middle-aged population.     

Refractive error and visual outcome after cataract extraction.

PURPOSE: To determine the range of biometry prediction error of the postoperative refraction and the visual outcome after cataract surgery. SETTING: Postgraduate teaching hospital. METHODS: Refraction and visual outcomes were recorded prospectively for a consecutive case series of 1817 cataract procedures. Complete preoperative and postoperative data were available for 1676 eyes (92.4%). The paired mean error of the difference between the predicted and achieved refraction, the percentages falling within +/-0.50 diopter (D), +/-1.00 D, and +/-2.00 D, and the values that contained 99% of data points were then calculated. The number that achieved a final Snellen visual acuity of 6/12 was determined in all eyes and in eyes without preoperative ocular comorbidity. This analysis was repeated in 1265 eyes that received a single intraocular lens (IOL) design (C10UB/C11UB) after phacoemulsification through a clear corneal incision. RESULTS: The paired mean error of the difference between the predicted and achieved postoperative refraction in all eyes was -0.32 D +/- 1.05 (SD); 72.3% of eyes were within +/-1.00 D of the planned refraction, with bounds of 99% of observation of +2.92 D and -3.98 D. In the single IOL group, the paired mean error was -0.32 +/- 0.94 D; 74.2% of eyes fell within +/-1.00 D of the planned refraction, with bounds of 99% of observation of +2.54 D and -3.81 D. Axial length did not determine the magnitude of the biometry prediction error. At discharge from the service, 86.9% of all eyes and 95.4% of eyes without preoperative ocular comorbidity achieved a final corrected Snellen acuity of 6/12. CONCLUSION: These data provide benchmark information that can be used to monitor clinical practice.     

Conductive keratoplasty for the correction of low to moderate hyperopia: 1-year results on the first 54 eyes

OBJECTIVE: To document the 1-year postoperative clinical results of the safety, efficacy, and stability of conductive keratoplasty (CK) to correct low to moderate hyperopia. DESIGN: Prospective, nonrandomized, self-controlled trial. PARTICIPANTS: Five surgeons at four centers performed CK on the first 54 eyes of a multicenter, 2-year clinical trial. Treated eyes had +0.875 to +4.00 diopters (D) of hyperopia and < or =0.75 D of cylinder. The nature of this procedure was explained to all participating patients who signed informed consent forms prior to undergoing the procedure. INTERVENTION: Low energy, high-frequency current was applied directly into the peripheral corneal stroma through a delivery tip inserted at 16 or more treatment spots. An early nomogram was used for the first 54 eyes with an intended refraction of plano. MAIN OUTCOME MEASURES: Data from all 54 eyes were analyzed for safety and stability. A subset of 30 of the 54 eyes was found that had been treated with the appropriate number of spots with the early nomogram. These eyes were categorized as current nomogram eyes; the data for these eyes were analyzed for efficacy and predictability, as well as stability and safety. All patients reported on satisfaction and quality of vision after surgery. RESULTS: Preoperatively, the manifest refractive spherical equivalent refraction (MRSE) of the 30 current nomogram eyes was +1.57 D. At 1 year postoperatively, uncorrected visual acuity was 20/20 or better in 57% of the eyes and 20/40 or better in 93%. The MRSE was within 0.50 D in 46%, within +/-1.00 D in 93%, and within +/-2.00 D in 100%. No eye lost > or =2 lines of best spectacle-corrected visual acuity at 1 year postoperatively nor had an induced cylinder of > or =2.00 D. The MRSE changed a mean of 0.25 D +/- 0.43 between 3 and 6 postoperative months, 0.16 D +/- 0.38 between 6 and 9 postoperative months, and 0.07 D +/- 0.38 between 9 and 12 postoperative months. Refractive stability appeared to be attained by 6 months postoperatively. CONCLUSIONS: Conductive keratoplasty appears to be safe, effective, and stable for correcting low to moderate spherical hyperopia. Stability appeared by the 6-month follow-up visit. For the eyes treated with the current CK nomogram, uncorrected visual acuity, predictability, and stability are as good as or better than those obtained with hyperopic laser in situ keratomileusis or noncontact laser thermal keratoplasty.     

Changes in astigmatism after congenital cataract surgery and intraocular lens implantation using scleral tunnel incision

PURPOSE: To evaluate the post-operative changes in astigmatism in pseudophakic eyes in children. Only eyes with astigmatism of 3.0 D or more were included in the study. METHODS: The charts of children who had undergone surgery for non-traumatic cataract, using a scleral tunnel method were retrospectively reviewed. In 11 eyes with astigmatism of 3.0 D or more, the refraction was tested and recorded at 1 week, 3 months and 5 months post-operatively. The paired t-test was used to compare between the variables. RESULTS: Mean astigmatism 1 week post-operatively was 5.8 +/- 3.6 D (range 3.0-14.0 D). Thereafter, the astigmatic component of the refractive error underwent a spontaneous steady decline, reaching a mean value of 2.1 +/- 1.3 D (range 1-4.0 D) 5 months after surgery. The change in the difference between the mean values at 1 week and at 5 months was statistically significant (P < 0.005). CONCLUSION: Children who underwent congenital cataract surgery and intraocular lens implantation showed a significant spontaneous reduction in astigmatism post-operatively.     

Changes in keratometric corneal power and refractive error after laser thermal keratoplasty

PURPOSE: To evaluate the effect of laser thermal keratoplasty (LTK) on corneal power and refractive error to develop a logical approach to calculating accurate intraocular lens (IOL) power for cataract surgery. SETTING: Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. METHODS: Laser thermal keratoplasty was performed in 27 eyes of 23 patients. Preoperatively and postoperatively, the refractive error was measured and the corneal power obtained by manual keratometry and topography. The changes in keratometric corneal power and refractive error after LTK were compared. RESULTS: The mean age of the 15 women and 8 men was 45.0 years +/- 4.6 (SD) (range 43 to 61 years). The mean preoperative refractive error was +1.43 +/- 0.97 diopters (D) (range 0 to +3.63 D) at the spectacle plane and +1.46 +/- 1.01 D (range 0 to +3.79 D) at the corneal plane. The mean postoperative refractive error was -0.44 +/- 1.07 D (range -2.24 to +2.18 D) at the spectacle plane and -0.44 +/- 1.08 D (range -2.18 to +2.23 D) at the corneal plane. After surgery, corneal powers measured by manual keratometry were significantly smaller than those measured by topography (P<.001) and refractive error changes were significantly smaller than keratometric changes (P<.001). CONCLUSIONS: After LTK, corneal power measured by manual keratometry was smaller than that measured by corneal topography and changes in corneal power measured by conventional keratometric instruments were greater than changes in refractive error. This difference should be considered in calculating IOL power in post-LTK eyes to prevent undesirable hyperopia after cataract surgery.     

Conductive keratoplasty for the correction of residual hyperopia after LASIK

PURPOSE: To report the 6-month results concerning efficacy, safety, predictability, and stability of conductive keratoplasty for the correction of residual hyperopia after corneal refractive surgery. METHODS: A total of 35 eyes (26 patients) with residual hyperopia after corneal refractive surgery ranging between +1.00 to +4.75 diopters (D) of spherical equivalent refraction were enrolled in the study and underwent conductive keratoplasty following a modified nomogram. RESULTS: Variables and data were available for all eyes at 6 months postoperatively. A total of 24 (69%) eyes had uncorrected visual acuity (UCVA) of > or = 20/40, and 10 (29%) eyes had UCVA of 20/20. Manifest refractive spherical equivalent was within +/- 0.50 D in 17 (49%) eyes and within +/- 1.00 D in 25 (71%) eyes in cases of previous hyperopic LASIK; the optical zone was significantly increased. CONCLUSIONS: Using a modified nomogram, conductive keratoplasty for correction of residual hyperopia was effective, but predictability was not satisfactory and safety needs to be established.     

Clinical evaluation of the Topcon BV-1000 automated subjective refraction system.

BACKGROUND: The BV-1000 is a new instrument that performs binocular autorefraction and subjective refraction. The aim of the study was to evaluate the accuracy of the BV-1000 compared with subjective refraction without cycloplegia and the repeatability of the BV-1000 in subjects without cycloplegia. METHODS: BV-1000 binocular autorefraction (mean of three measures) and automated subjective refraction was performed on 100 eyes and compared with practitioner subjective refraction. After BV-1000 assessment, the result was modified by the investigator in the form of a binocular addition; the practitioner was masked as to the result of the BV-1000. Repeatability was evaluated by comparing the test-retest data on 40 eyes. Refraction data were converted into Fourier component terms: mean spherical equivalent (MSE), J0, J45, and vector dioptric difference (VDD). RESULTS: Mean difference of MSE (BV-1000 subjective vs. practitioner) was 0.05 +/- 0.35 D (p = 0.13), whereas after binocular addition, the mean difference in MSE was -0.01 +/- 0.21 D (p = 0.67). The mean difference of MSE (BV-1000 objective vs. practitioner) was +0.10 +/- 0.37 D (p < 0.05). Mean difference in J0 and J45 was -0.03 +/- 0.12 D (p = 0.09) and -0.02 +/- 0.10 D (p = 0.06), respectively. More than 95% of cylinder powers were within +/- 0.50 D. The median VDD was 0.35 D (range, 1.38 D; interquartile range, 0.31) for comparisons of BV-1000 subjective refraction and the practitioner. A median VDD of 0.25 D (range, 1.06 D; interquartile range, 0.16) was found after binocular addition correction. There was no statistically significant difference (p = 0.73) in spherical intereye difference between BV-1000 subjective and subjective refraction. Mean spherical intereye difference (spherical balancing error) between the BV-1000 and practitioner subjective refraction was -0.02 +/- 0.24 D. Repeatability as described by the mean difference between occasions for MSE was found to be -0.06 +/- 0.19 D, -0.02 +/- 0.08 D for J0, and -0.03 +/- 0.07 D for J45. CONCLUSIONS: The subjective refraction routine within the BV-1000 improves the results of simultaneous binocular autorefraction data. The BV-1000 provides an accurate and repeatable measure of subjective refraction after binocular addition.