Juan C. Ondategui

Optical quality one month after verisyse and Veriflex phakic IOL implantation and Zeiss MEL 80 LASIK for myopia from 5.00 to 16.50 diopters.

PURPOSE To evaluate the eyes optical quality after phakic intraocular lens (IOL) implantation and LASIK for moderate to high myopia. METHODS The retinal image quality of 45 patients was evaluated after undergoing one of three surgical procedures (9 patients with Verisyse IOL [AMO] implants, 11 patients with Veriflex IOL [AMO] implants, and 25 patients who underwent LASIK). Patients were aged <40 years, had at least 5.00 diopters of myopia, and had preoperative best spectacle-corrected visual acuity and postoperative uncorrected visual acuity better than 20/30. The eyes optical quality was measured using the Optical Quality Analysis System (OQAS, Visiometrics S.L.), which is an instrument based on the double-pass technique. Measurements were performed before surgery and 1 day and 1 month after surgery. RESULTS Optical quality worsened noticeably 1 day after surgery with the Verisyse IOL with a 50% to 60% loss, most likely due to the large incision and the presence of sutures in most eyes. The LASIK technique and Veriflex IOL implant did not cause as remarkable a decrease in optical quality (20% to 25% loss). One month after surgery, the optical quality of patients with IOL implants was high, although some surgically induced astigmatism remained, especially in the Verisyse patients. Conversely, LASIK patients had slightly lower optical quality, with optical parameters that represented 90% of their initial value. CONCLUSIONS Verisyse and Veriflex phakic IOL implantation and LASIK are both safe and effective in correcting moderate to high myopia, but they involve different processes of optical quality recovery. One day after surgery, the Verisyse IOL implantation significantly reduced the eyes optical quality, mainly due to the larger incision required and the higher number of sutures used. This reduction was not as remarkable with the other two techniques. However, 1 month after surgery, patients with IOL implants recovered more optical quality than LASIK patients.

Optical quality and intraocular scattering in a healthy young population

Background:  We objectively assessed the optical quality and intraocular scattering by means of parameters provided by a clinical double‐pass system in healthy young subjects and thereby we obtained new reference data for clinical diagnosis. We calculated normal values of neural contrast sensitivity function (nCSF) from the measured modulation transfer function (MTF) and the contrast sensitivity function (CSF).

Effect of laser in situ keratomileusis on vision analyzed using preoperative optical quality

PURPOSE: To evaluate the effect on vision of laser in situ keratomileusis (LASIK) based on preoperative optical quality. SETTING: Universitat Politècnica de Catalunya, Terrassa, and Barcelona Institute of Ocular Microsurgery, Barcelona, Spain. DESIGN: Comparative case series. METHODS: The relative change in optical quality and visual acuity were evaluated in eyes that had LASIK for myopia. The optical quality was assessed before and 3 months after surgery using parameters provided by a double‐pass system. Patients were classified into 4 groups by preoperative optical quality: low (Group 1), moderate (Group 2), high (Group 3), and very high (Group 4). RESULTS: The study evaluated 25 patients (50 eyes). The optical quality parameters improved postoperatively in Group 1 and Group 2, with the improvement ranging from 15% to 21% and from 13% to 17%, respectively. The preoperative and postoperative optical quality in Group 3 was similar. The optical quality in Group 4 worsened significantly by percentages ranging from −20% to −26%. Although visual acuity had the same trend, there were no statistically significant changes. CONCLUSION: The changes in optical quality after LASIK surgery depended on the patient’s preoperative optical quality; visual acuity showed the same trend, although no change was significant. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Optical quality after myopic photorefractive keratectomy and laser in situ keratomileusis: Comparison using a double-pass system

PURPOSE: To use a double‐pass system to compare the optical quality after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for mild to moderate myopia. SETTING: Universitat Politècnica de Catalunya, Terrassa, Barcelona Institute of Ocular Microsurgery, Barcelona, Spain. DESIGN: Comparative case series. METHODS: Optical quality was assessed with a clinical double‐pass system preoperatively and 3 months after PRK or LASIK. The modulation transfer function (MTF), retinal image quality parameters (MTF cutoff frequency, Strehl ratio), and intraocular scattering (objective scatter index [OSI]) were calculated. RESULTS: This study evaluated 34 eyes that had PRK and 55 eyes that had LASIK. Both PRK and LASIK had a statistically significant impact on retinal image quality, although no significant differences between the techniques were observed. The MTF at 30 cycles per degree decreased by a factor of 1.50 in the PRK group and by a factor of 1.32 in the LASIK group. The MTF cutoff frequency decreased by a factor of 1.04 in the PRK group and by a factor of 1.06 in the LASIK group. The Strehl ratio decreased by a factor of 1.10 and 1.07, respectively. Photorefractive keratectomy and LASIK increased the objective scatter index by factors of 1.48 and 1.57, respectively. Significant correlations between the preoperative refraction and the OSI were found. CONCLUSIONS: Retinal image quality was similarly reduced with PRK and LASIK, with no significant differences between the 2 methods. Some PRK patients had a residual refractive error that might have been related to corneal‐wound healing still present 3 months postoperatively. Financial Disclosure: Dr. Arjona is an investor in and Drs. Güell and Pujol are investors in and consultants to Visiometrics S.L., Terrassa, Spain. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Grading nuclear, cortical and posterior subcapsular cataracts using an objective scatter index measured with a double-pass system

Purpose To evaluate objectively intraocular scattering in eyes with nuclear, cortical and posterior subcapsular cataracts by means of an objective scatter index (OSI) obtained from double-pass images. To compare the results with those obtained using clinical conventional procedures. Methods In this prospective, observational, cross-sectional, non-consecutive case series study, 188 eyes with cataracts of 136 patients were analysed (123 eyes had nuclear, 41 eyes had cortical and 24 eyes had posterior subcapsular cataracts). The control group consisted of 117 eyes of 68 healthy patients. Patient examination included subjective refraction, best spectacle-corrected visual acuity (BSCVA), cataract grade using the lens opacities classification system III (LOCS III) and OSI. Results We found a decrease in the BSCVA and an increase in the OSI with increasing cataract grade. Statistically significant differences were observed when the OSI of eyes without cataracts and those with different LOCS III were compared. The comparison between the OSI and LOCS III reported good percentages of agreement regarding the number of eyes classified in equivalent levels: 72.4% (nuclear cataracts), 86.6% (cortical cataracts) and 84.3% (posterior subcapsular cataracts). A non-linear regression model was applied between OSI and BSCVA, which resulted in the following multiple correlation coefficients: r=0.878 (nuclear), r=0.843 (cortical) and r=0.844 (posterior subcapsular). Conclusions The results of the study showed that OSI is a useful parameter for evaluating large amounts of intraocular scattering that can be used, in combination with other conventional procedures, as a valuable tool in clinical practice to grade cataracts objectively.

Double-pass technique and compensation-comparison method in eyes with cataract

Purpose To clinically assess the objective scatter index (OSI) obtained from double‐pass images and the log(s) parameter measured with the direct compensation‐comparison psychophysical technique in eyes with cataract. Setting Ophthalmology Service, Terrassa Hospital, Barcelona, Spain. Design Prospective observational case series. Methods The analysis comprised eyes diagnosed with nuclear, cortical, or posterior subcapsular cataracts and healthy eyes (control group). Patient examinations included assessment of the manifest subjective refraction, corrected distance visual acuity, contrast sensitivity, and cataract grade using the Lens Opacities Classification System III (LOCS III) score. The protocol also included the straylight (log[s]) measured by the C‐Quant device, measurement of the objective optical quality (Strehl ratio and modulation transfer function cutoff frequency), and the OSI (HD Analyzer). Results Significant correlations with LOCS III classification were found in terms of log(s) and OSI, although they were slightly stronger with OSI for all cataract types, which could be attributable to higher‐order aberrations. The OSI and log(s) shared approximately 44% of the scattering estimation and to coincide on the visual function decline with scattering for the 3 cataract types evaluated. Limits to discriminate between healthy and cataractous eyes and sensitivity and specificity values were 1.15 (sensitivity 91%, specificity 100%) for log(s) and 1.18 (sensitivity 89%, specificity 100%) for OSI (P < .05). Conclusions Both instruments provide complementary information to diagnose cataracts and follow patients. Although backscattered light from deeper retinal layers can have an effect on OSI, the double‐pass image provides information to grade different types of cataract when assessing cataractous eyes for treatment. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.