Daniel Badoza

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.

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.

Phacoemulsification using the burst mode

Purpose: To compare the amount of ultrasound (US) energy required for burst mode and pulse mode during nuclear fragment emulsification. Setting: Instituto de la Visión, University of Buenos Aires, Buenos Aires, Argentina. Methods: The ultrasound time (UST) and effective US power (USP) used by 2 surgeons were retrospectively compared. Nuclear fragments were emulsified using the pulse mode in 82 cases (Group 1) and the burst mode in 118 cases (Group 2). The 2 groups were divided according to nuclear hardness: 0 to 2+ (subgroups 1a and 2a) or 3+ to 4+ (subgroups 1b and 2b). The difference in nuclear hardness between Groups 1 and 2 was not statistically significant. Results: The mean UST and USP were, respectively, 1.64 minutes ± 0.98 (SD) at 10.53% ± 4.46% in subgroup 1a and 0.56 ± 0.46 minutes at 10.51% ± 5.80% in subgroup 1b. The respective means were 2.94 ± 1.36 minutes at 15.14% ± 4.49% in subgroup 2a and 0.75 ± 0.52 minutes at 10.04% ± 3.12% in subgroup 2b. The differences between subgroups were statistically significant except between subgroups 2a and 2b. Conclusion: The burst mode increased US efficiency, especially when used for hard cataracts.

Deep sclerectomy with a collagen implant using the excimer laser

We describe a new technique of nonpenetrating glaucoma surgery that uses the excimer laser to reduce the risk of perforating the trabeculo-Descemets membrane. With this technique, the ablation is precise and homogeneous. A collagen device is sutured over the scleral bed to create an outflow pathway for aqueous humor drainage. After a superficial scleral flap is dissected with a diamond knife, the sclera, under direct visualization, is ablated with the excimer laser over Schlemms canal until aqueous humor percolates through from the anterior chamber. A collagen device is placed over the sclera to allow the aqueous humor to flow from the anterior chamber through the trabeculo-Descemets membrane. The preliminary results show a drop in intraocular pressure to the middle teens.

Orbital leiomyoma: a case report.

PURPOSE Leiomyoma is a benign tumor derived from smooth muscle, most frequently occurring in the uterus and gastrointestinal system. This report discusses clinical and pathologic findings in a 56-year-old man with orbital leiomyoma. METHODS Case review. RESULTS A lateral orbitotomy was performed. Immunohistochemical staining for actin and desmin was positive result. There was no evidence of recurrence during a two-year follow-up interval. CONCLUSIONS Leiomyoma is a benign tumor of low incidence because there is little smooth muscle in the orbit. The differential diagnosis must include any fully encapsulated orbital tumor. Prognosis after surgical excision is favorable.

Axial length scanning: Laser interferometry versus ultrasound biometry

In cataractous patients, the authors measured the axial length (AL) using both partial coherence laser interferometry (PCLI) and ultrasound biometry (UB), the latter performed by both an experienced and inexperienced operator. Both sets of AL measurements were compared to theoretical (calculated) AL values. AL measurements obtained with PCLI are as reliable as those recorded by an experienced operator using UB.