Carlos Argento

Corneal ectasia after laser in situ keratomileusis

Purpose: To describe 7 patients who developed ectasia following laser in situ kerato‐mileusis (LASIK). Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: In this retrospective study of 7 patients, visual acuity, refraction, pachymetry, and corneal topography were examined before and after the refractive procedure and the occurrence of ectasia. Results: Two of the 7 patients required penetrating keratoplasty. Ectasia developed within a mean of 1.02 years ± 0.31 (SD). The clinical evolution of ectasia and the potential physiopathogenic causes of ectasia are described. Conclusion: Ectasia should be considered a potential complication of LASIK that is closely related to corneal thickness, but another variable, the optical zone diameter, should also be considered.

Intraocular lens power calculation after refractive surgery

Purpose: To analyze the results of phacoemulsification cataract surgery in eyes that had had refractive surgery and to compare the predictability of various methods of intraocular lens (IOL) power calculation. Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: The study involved 7 cases that had phacoemulsification after radial keratotomy or laser in situ keratomileusis. The spherical equivalent (SE) and visual acuity were evaluated preoperatively and postoperatively to assess the changes before cataract development. The IOL power calculated with conventional keratometry (CK), adjusted keratometry, the clinical history method (CHM), corneal topography (CT), and the contact lens method (CLM) was compared with the final refractive and keratometric results measured with the BackCalcs (Holladay® IOL Consultant Program, Holladay Consulting, Inc.) to assess the accuracy and predictability of each method. Results: The mean SE was –4.82 diopters (D) ± 5.13 (SD) before phacoemulsification and +0.19 ± 1.01 D after phacoemulsification, and the mean best corrected visual acuity was 0.39 ± 0.07 (20/50) and 0.80 ± 0.06 (20/25), respectively. Conclusions: Post‐phacoemulsification refraction in cases with previous refractive surgery appeared to be predictable when the appropriate calculation method was applied. When all the data were available, the CHM provided the best results. Adjusted keratometry and CT seemed to be more accurate than CK and the CLM.

Laser in situ keratomileusis for hyperopia.

Purpose: To evaluate the results of laser in situ keratomileusis (LASIK) to treat hyperopia. Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: This nonrandomized study comprised 679 eyes of 321 patients having LASIK. Patients were divided into three groups based on preoperative spherical equivalent: Group A (low hyperopia, 2.00 diopters [D] or less); Group B (moderate hyperopia, between 2.00 and 3.00 D); Group C (high hyperopia, more than 3.00 D). The following were measured postoperatively: uncorrected visual acuity (UCVA); best spectacle‐corrected visual acuity (BSCVA); refraction (evolution and distribution); lines of visual acuity gained and lost. Follow‐up was 1 month in 79.4% of cases, 3 months in 75.5%, 6 months in 68.5%, and 1 year in 38.3%. Results: Six months after LASIK, 100% of cases in Group A, 95.3% in Group B, and 71.4% in Group C were within ± 1.00 D of emmetropia; UCVA was 20/40 or better in 94.1, 100, and 87.8%, respectively. The percentage losing or gaining 0 ± 1 line of BSCVA was 100, 97.6, and 100, respectively. Conclusions: Laser in situ keratomileusis was predictable and safe in the treatment of low and moderate hyperopia.

Sequential in Vivo Confocal Microscopy Study of Corneal Wound Healing After Cross-Linking in Patients with Keratoconus

PURPOSE To evaluate the short- and long-term sequential histological changes of the cornea in vivo after corneal collagen cross-linking (CXL) in patients with keratoconus. METHODS Eighteen patients with keratoconus (Amsler-Krumeich classification: stages I, II, and III) underwent CXL with riboflavin/ultraviolet A (UVA) in one eye. The corneas were examined preoperatively and within 5 hours, 7 and 14 days, and 1, 3, 6, 9, 12, 18, 24, and 36 months after the procedure using in vivo confocal microscopy. RESULTS Early changes included edema, superficial nerve loss, cellular modifications, and isolated endothelial damage. At intermediate time points, there was nerve fiber regeneration, increased reflectivity of the extracellular matrix, enlarged keratocytes and extracellular deposits, and remodeling of the endothelial layer (two eyes). At later time points, loss of keratocytes and remodeling of the extracellular deposits were noted. CONCLUSIONS Although the cornea has no significant tissue modifications clinically after CXL, this study has shown that corneal wounding by riboflavin/UVA collagen CXL induces cellular wound-healing mechanisms and alters the normal structure and cellularity of the cornea for up to 36 months.

Comparison of laser epithelial keratomileusis with and without the use of mitomycin C.

PURPOSE To analyze the results of prophylactic intraoperative use of mitomycin C (MMC) in laser epithelial keratomileusis (LASEK). METHODS A retrospective analysis of 30 LASEK cases that received MMC 0.02% intraoperatively (MMC group) was performed and compared to the results obtained in 28 LASEK cases not receiving MMC (no MMC group). Mitomycin C was placed in contact with the ablation zone for 75 seconds with an imbibed microsponge. Both groups received postoperative fluorometholone for 3 months. Preoperative spherical equivalent refraction was -5.72 +/- 2.82 diopters (D) in the MMC group and -5.81 +/- 2.74 D in the no MMC group. Best spectacle-corrected visual acuity was 0.88 +/- 0.12 in the MMC group and 0.88 +/- 0.13 in the no MMC group. RESULTS Spherical equivalent refraction at 6 months postoperatively was +0.11 +/- 0.13 D in the MMC group and +0.09 +/- 0.37 D in the no MMC group. Best spectacle-corrected visual acuity was 0.90 +/- 0.13 in the MMC group and 0.88 +/- 0.13 in the no MMC group. Uncorrected visual acuity (UCVA) > or = 20/40 was obtained in 93.3% of cases in the MMC group and in 89.3% of cases in the no MMC group; UCVA > or = 20/25 was achieved in 76.6% of cases in the MMC group and in 71.4% of cases in the no MMC group. Haze incidence for the MMC group was: trace: 0%, Grades I: 0%, II: 0%, III 0%, IV: 0%, and for the no MMC group: trace: 17.9%, Grades I: 3.6%, II: 0%, III: 0%, IV: 0%. A statistically significant difference (P<.001) was noted in haze intensity between the MMC group and no MMC group. CONCLUSIONS Prophylactic use of intraoperative MMC in LASEK significantly decreases haze incidence.

Optic capture of the AcrySof intraocular lens in pediatric cataract surgery

Purpose: To assess the results of acrylic intraocular lens (IOL) optic capture in children with cataract. Setting: Department of Ophthalmology, Hospital de Clínicas José de San Martín, and Instituto de la Vision, School of Medicine, University of Buenos Aires, Argentina. Methods: Eight children had cataract surgery. After lens and cortex aspiration, an AcrySof® (Alcon) IOL was implanted in the bag. A primary posterior capsulorhexis was performed. The optic edges were slipped through the posterior capsule leaflets. Clarity of the visual axis, preoperative and postoperative best corrected visual acuities (BCVAs), and refraction were evaluated. Results: The visual axis remained clear in all cases. No case required a secondary procedure. The mean preoperative BCVA was 0.06 ± 0.06 (SD). Postoperatively, the mean BCVA was 0.88 ± 0.11 and the mean spherical equivalent, +0.62 ± 1.31. The mean follow‐up was 28.9 ± 5.3 months. Conclusion: Results show that the optic of an acrylic IOL may be captured through a posterior capsulorhexis in pediatric cataract surgery, combining the advantages of optic capture with a smaller incision and a decreased inflammatory response.

State-of-the-art phacoemulsification performed by residents in Buenos Aires, Argentina

PURPOSE To analyze the learning curve for state-of-the-art phacoemulsification performed by residents. SETTING Department of Ophthalmology, Hospital de Clinicas José de San Martin, University of Buenos Aires, Buenos Aires, Argentina. METHODS The records of patients having phacoemulsification performed by residents from June 1996 to January 1998 were reviewed for preoperative and postoperative best corrected visual acuities and the occurrence of complications. The phacoemulsification technique used for the first 35 surgeries of each resident was compared with that of their last 35 surgeries. RESULTS The records showed 249 cases of phacoemulsification by residents. Mean preoperative best corrected visual acuity was 0.19 +/- 0.19 (SD). One month postoperatively, it was 0.86 +/- 0.2. Nuclear fracture was performed in a mean of 28.33 +/- 5.0 of the first 35 surgeries by each resident, whereas chopping techniques were used in a mean of 23.33 +/- 1.5 of the last 35 cases. Vitreous loss occurred in 2.8% of cases. CONCLUSION Residents learned cracking and chopping phacoemulsification techniques safely with satisfactory outcomes.

Treatment of hyperopic astigmatism

Purpose: To analyze the results after laser‐assisted in situ keratomileusis (LASIK) treatment for positive cylinder at the flattest meridian. Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: A prospective, nonrandomized study was conducted. Patients were divided into three groups: (1) simple hyperopic astigmatism (SHA); 15 eyes with a mean preoperative cylinder of +3.37 diopters (D) ± 1.62 (SD); compound hyperopic astigmatism (CHA); 75 eyes with a mean preoperative cylinder of +3.34 ± 1.39 D; (3) mixed astigmatism (MA); 73 eyes with a mean preoperative cylinder of +3.45 ± 2.15 D. In all eyes, treatment of the cylinder was performed at the flattest meridian by LASIK using the Chiron‐Technolas Keracor 116/117 laser. The following parameters were analyzed over time: uncorrected visual acuity; best corrected visual acuity; correction of the spherical equivalent and the cylinder; lines of visual acuity gained and lost. Results: Six months after the procedure, refractive cylinder was reduced to +0.58 1.22 D in the SHA group, +0.12 ± 1.23 D in the CHA group, and −0.11 ± 1.28 D in the MA group. Uncorrected visual acuities were 20/20 or 20/25 in 66.7, 60.4, and 76.5% of the groups, respectively. Conclusions: Use of the LASIK technique with the Keracor laser to treat positive cylinder at the flattest meridian corrected simple and compound hyperopic astigmatism and mixed astigmatism with good predictability and safety. This treatment has not produced a hyperopic refractive change at the opposite meridian.

Incidence of postoperative posterior capsular opacification with types of senile cataracts.

ABSTRACT The most frequent postoperative complication in extracapsular cataract surgery is opacification of the posterior capsule. The purpose of this study was to correlate the frequency of capsular opacification with each kind of senile cataract. A total of 566 eyes with cataracts were studied. They had been operated on between 1980 ‐ and 1990 using the extracapsular, intercapsular, and phacoemulsification techniques. Our results confirm that senile complete cataracts (mature cataracts) had a significantly lower tendency to produce postoperative capsular opacification than other cataract types (nuclear, cortical, posterior subcapsular).

Comparison of optical zones in hyperopic laser in situ keratomileusis: 5.9 mm versus smaller optical zones.

PURPOSE To compare the results of hyperopic laser in situ keratomileusis (LASIK) with a 5.9 mm optical zone (OZ) with those with smaller zones (4.4 to 5.5 mm). SETTING Instituto de la Visión, Buenos Aires, Argentina. METHODS The results of LASIK with a 5.9 mm OZ (147 cases) were compared with those in a previously reported group treated with OZs of 4.4 to 5.5 mm (679 cases). In the 5.9 mm group, 31.3% (46 eyes) had low hyperopia, 46.9% (69 eyes) had moderate hyperopia, and 21.8% (32 eyes) had high hyperopia. In the smaller OZ group, follow-up was 1 month in 79.4% (539 eyes), 3 months in 75.5% (501 eyes), 6 months in 68.5% (465 eyes), and 1 year in 38.3% (260 eyes). The hyperopic population studied was divided into 3 subgroups based on the preoperative spherical equivalents of the manifest refraction: subgroup A, low hyperopia: < or = +2.0 diopters (D); subgroup B, moderate hyperopia: +2.0 to +3.0 D; and subgroup C, high hyperopia: > +3.0 D. The following parameters were measured postoperatively: uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction (evolution and distribution), and visual acuity lines gained and lost. RESULTS The preoperative mean spherical equivalents in the 5.9 mm OZ group were +1.47 +/- 0.41 (SD) (subgroup A); +2.98 +/- 0.41 (subgroup B); and +5.13 +/- 0.61 (subgroup C). In the smaller OZ group, they were +1.31 +/- 0.74, +2.56 +/- 0.28, and +5.28 +/- 0. 69, respectively. At 12 months, the distribution of eyes in the 5.9 mm OZ group with refractions within +/-1.0 D were as follows: subgroup A, 100%; subgroup B, 100%; and subgroup C, 94.2%. In the smaller OZ group, the distributions were 100%, 95.3%, and 71.4%. In the 5.9 mm and the smaller OZ groups, the UCVA was 20/40 or better in 92.0% and 81.8% of eyes, respectively, in subgroup A; 94.6% and 100%, respectively, in subgroup B; and 76.5% and 77.9%, respectively, in subgroup C. The percentage of eyes with 0 +/- 1 line of BCVA 12 months after the procedure was also determined in the 5.9 mm OZ group and compared with the percentages in the smaller OZ group. CONCLUSION Results of hyperopic LASIK with a 5.9 mm OZ in eyes with low, moderate, and high hyperopia are more stable, predictable, and safe than those in eyes with OZs smaller than 5.9 mm.