Changes in straylight after cataract surgery.

PURPOSE: To investigate straylight in the immediate postoperative period after cataract surgery. SETTING: Amphia Hospital, Breda, the Netherlands. DESIGN: Prospective, comparative, single-arm, single-center, single-surgeon study. METHODS: Patients underwent cataract surgery on both eyes. 1 eye was randomly selected for implantation with a Clareon CNA0T0 intraocular lens (IOL); the fellow eye received a Vivinex XY1 IOL. Straylight was measured with the C-Quant straylight meter. RESULTS: 25 patients were included. Preoperatively, 1 day, 1 week, 1 month, and 3 months postoperatively, eyes with a CNA0T0 IOL had straylight levels (mean ± SD) of 1.48 ± 0.23, 1.26 ± 0.20, 1.06 ± 0.19, 1.11 ± 0.25, and 1.09 ± 0.20 log(s), respectively. For eyes with an XY1 IOL, these values were 1.48 ± 0.21, 1.41 ± 0.41, 1.10 ± 0.20, 1.13 ± 0.20, and 1.16 ± 0.20 log(s), respectively. From 1 week postoperatively, straylight values did not change (1 week vs 3 months: P = .40 and P = .14 and 1 month vs 3 months: P = .74 and P = .50 for CNA0T0 and XY1, respectively). The Pearson correlation coefficient for straylight values between the 2 eyes of individual subjects was 0.80 at 3 months. CONCLUSIONS: Straylight levels can be considered stable 1 week after cataract surgery. We believe it is safe to use straylight measurements 1 month postoperatively for clinical trials. Straylight is highly correlated between the 2 eyes of an individual postoperatively.

Nd:YAG laser capsulotomy rates in the Netherlands: practice variation and association with physician practice styles.

PURPOSE: To determine the practice variation in the rate of Nd:YAG laser capsulotomy within 1 year after cataract surgery and to identify possible associations with physician practice styles. SETTING: All hospitals and private clinics in the Netherlands. DESIGN: Retrospective observational study. METHODS: In the national medical claims database, we identified all laser capsulotomies performed in the Netherlands within a year after cataract surgery in the years 2016 and 2017. Centers with the lowest and highest percentages of Nd:YAG laser capsulotomies were interviewed on their physician practice styles related to the development of posterior capsule opacification. RESULTS: The incidence of Nd:YAG laser capsulotomy varied between 1.2% and 26.0% in 2016 (median 5.0%) and between 0.9% and 22.7% in 2017 (median 5.0%). The rate of capsulotomy was highly consistent over time for each center (Pearson correlation coefficient, 0.89, P < .001). In general, ophthalmology centers with a high rate of Nd:YAG laser capsulotomy more often did not (routinely) polish the posterior lens capsule, performed cortex removal with coaxial irrigation/aspiration (I/A, instead of bimanual), and more often used hydrophilic intraocular lenses (IOLs) (compared with only using hydrophobic IOLs). CONCLUSIONS: We found a significant practice variation in performing Nd:YAG laser capsulotomy within 1 year after cataract surgery in the Netherlands. Routinely polishing the posterior capsule, using bimanual I/A, and the use of hydrophobic IOLs are associated with a lower incidence in Nd:YAG laser capsulotomy. Incorporating these practice styles may lower the practice variation and thus prevent added medical burden for the patient and decrease costs.

Straylight due to intraocular lens opacification in a patient with asteroid hyalosis.

PURPOSE: To report a rare case of intraocular lens (IOL) calcification in the presence of asteroid hyalosis with in-vivo measurements of straylight before and after treatment. OBSERVATIONS: A patient with asteroid hyalosis presented with complaints of disability glare due to calcifications on the posterior surface of the IOL. Straylight, measured with the C-Quant, was 8.2x elevated compared to normal (log(s) 2.08). Dissolution of the posterior face IOL deposits was performed with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, resulting in a significant decrease in straylight (log(s) 1.76), congruent with the patient's subjective improvement. CONCLUSIONS AND IMPORTANCE: To the best of our knowledge, this is the first report describing a patient with an opacified IOL due to asteroid hyalosis with in-vivo measurements of straylight before and after treatment. It illustrates that awareness of glare complaints in patients with an opacified IOL is important, documentation with C-Quant measurements may be helpful in indicating treatment, evaluating the treatment, and following up the patient, and treatment with a Nd:YAG laser may dissolve the opacifications to a clinically satisfactory level.

Evaluation of an AI system for the automated detection of glaucoma from stereoscopic optic disc photographs: the European Optic Disc Assessment Study.

OBJECTIVES: To evaluate the performance of a deep learning based Artificial Intelligence (AI) software for detection of glaucoma from stereoscopic optic disc photographs, and to compare this performance to the performance of a large cohort of ophthalmologists and optometrists. METHODS: A retrospective study evaluating the diagnostic performance of an AI software (Pegasus v1.0, Visulytix Ltd., London UK) and comparing it with that of 243 European ophthalmologists and 208 British optometrists, as determined in previous studies, for the detection of glaucomatous optic neuropathy from 94 scanned stereoscopic photographic slides scanned into digital format. RESULTS: Pegasus was able to detect glaucomatous optic neuropathy with an accuracy of 83.4% (95% CI: 77.5-89.2). This is comparable to an average ophthalmologist accuracy of 80.5% (95% CI: 67.2-93.8) and average optometrist accuracy of 80% (95% CI: 67-88) on the same images. In addition, the AI system had an intra-observer agreement (Cohen's Kappa, κ) of 0.74 (95% CI: 0.63-0.85), compared with 0.70 (range: -0.13-1.00; 95% CI: 0.67-0.73) and 0.71 (range: 0.08-1.00) for ophthalmologists and optometrists, respectively. There was no statistically significant difference between the performance of the deep learning system and ophthalmologists or optometrists. CONCLUSION: The AI system obtained a diagnostic performance and repeatability comparable to that of the ophthalmologists and optometrists. We conclude that deep learning based AI systems, such as Pegasus, demonstrate significant promise in the assisted detection of glaucomatous optic neuropathy.

The significance of changes in pupil size during straylight measurement and with varying environmental illuminance / Importancia de los cambios del tamaño de la pupila durante la medición de la dispersión lumínica, con variación de iluminancia ambiental

Purpose: In this work, we investigated the pupillary conditions during straylight measurement, and the potential effect this might have on the measured straylight. Methods: Five young (26-29-years-old) and 15 older (50-68-years-old) individuals participated in this study. First, the pupil diameter of both eyes was measured at three room illuminances. Next, straylight was assessed at two room illuminances. Simultaneously, the change in pupil size of the fellow eye was registered by a camera. Results: Pupil size decreased with room illuminance and with age (both p < 0.05). The dependency of pupil size on age decreased as room illuminance increased (0.018 mm/year at 4 lux, 0.014 mm/year at 40 lux, and 0.008 mm/year at 400 lux illuminances). However, during straylight measurement, pupil sizes hardly differed between 4 and 40 lux illuminances. Respective pupil sizes corresponded with 399 and 451 lux adaptation on average. No statistically significant difference was found between the straylight under the two illuminances with average R2 = 0.85, p < 0.05. Conclusion: We conclude that the illuminance of the examination room during straylight assessment does not affect the outcome in normal eyes. In fact, under mesopic and scotopic conditions, the luminance of the test field is so much higher than that of the room so that it determines the pupil size. Regardless of the lighting level, straylight measured in a laboratory, is valid for photopic pupils at an adaptation level corresponding with about 400 lux room illuminance

Objetivo: En este trabajo investigamos las condiciones de la pupila durante la medición de la dispersión lumínica, así como el efecto potencial que ello podría tener sobre la dispersión lumínica medida. Métodos: En el estudio participaron cinco individuos jóvenes (de 26 a 29 años) y 15 mayores (de 50 a 68 años). En primer lugar, se midió el diámetro de la pupila de ambos ojos con tres iluminancias ambientales. A continuación, se evaluó la dispersión lumínica con dos iluminancias ambientales. De manera simultánea, se registró mediante una cámara el cambio del tamaño de la pupila del otro ojo. Resultados: El tamaño de la pupila se redujo con la iluminancia ambiental y la edad (p < 0,05 para ambos). La dependencia del tamaño de la pupila con la edad se redujo a medida que aumentaba la iluminancia ambiental (0,018 mm/año a iluminancias de 4 lux, 0,014 mm/año a 40 lux, y 0,008 mm/año a 400 lux). Sin embargo, durante la medición de la dispersión lumínica, los tamaños de la pupila difirieron escasamente entre iluminancias de 4 y 40 lux. Los tamaños de la pupila respectivos se correspondieron con una adaptación de 399 y 451 lux, de media. No se encontraron diferencias estadísticamente significativas entre la dispersión lumínica bajo las dos iluminancias y la media de R2 = 0,85, p < 0,05. Conclusión: Concluimos que la iluminancia de la sala de examen durante la valoración de la dispersión lumínica no afecta al resultado en ojos normales. De hecho, en condiciones mesópicas y fotópicas, la iluminancia del campo de prueba es muy superior a la de la sala, lo cual determina el tamaño de la pupila. Independientemente del nivel de iluminación, la dispersión lumínica medida en un laboratorio es válida para pupilas fotópicas a un nivel de adaptación correspondiente a una iluminancia ambiental de alrededor de 400 lux

Effects of clinical parameters on patient-reported outcome in cataract patients: a multicentre study.

PURPOSE: Ophthalmologists tend to evaluate the results of cataract surgery by focusing on the clinical visual and refractive outcomes and the incidence of complications, where patients' main interest might be their ability to perform daily activities. Therefore, there appears to be a need for optimizing effective communication between patients and ophthalmologist about the outcome of cataract surgery. The aim of this multicentre study was to determine the effects of whether the surgery was performed in one or two eyes, ocular comorbidity and per- and postoperative complications on visual function experienced by patients measured with the Catquest-9SF. METHODS: To measure patient-reported outcomes, Catquest-9SF data were collected between 2014 and 2015 in five Dutch hospitals. Data from 870 pairs of questionnaires - completed before and after cataract surgery - were compared with clinical data. Clinical data, retrieved from patients' medical files, consisted of one or two eye surgery, ocular comorbidity and per- and postoperative complications. RESULTS: Quality of vision improved more in patients who had surgery in both eyes and had fewer postoperative complications (both p < 0.001). We found a nonsignificant trend that quality of vision was worse when ocular comorbidity was present. No significant effect of peroperative complications was observed. CONCLUSION: Our results emphasize the added value of the Catquest-9SF as a tool for visual function experienced by patients; the additional information can complement clinical parameters to improve patient-centred approaches in clinical practice.

The significance of changes in pupil size during straylight measurement and with varying environmental illuminance.

PURPOSE: In this work, we investigated the pupillary conditions during straylight measurement, and the potential effect this might have on the measured straylight. METHODS: Five young (26-29-years-old) and 15 older (50-68-years-old) individuals participated in this study. First, the pupil diameter of both eyes was measured at three room illuminances. Next, straylight was assessed at two room illuminances. Simultaneously, the change in pupil size of the fellow eye was registered by a camera. RESULTS: Pupil size decreased with room illuminance and with age (both p<0.05). The dependency of pupil size on age decreased as room illuminance increased (0.018mm/year at 4 lux, 0.014mm/year at 40 lux, and 0.008mm/year at 400 lux illuminances). However, during straylight measurement, pupil sizes hardly differed between 4 and 40 lux illuminances. Respective pupil sizes corresponded with 399 and 451 lux adaptation on average. No statistically significant difference was found between the straylight under the two illuminances with average R2=0.85, p<0.05. CONCLUSION: We conclude that the illuminance of the examination room during straylight assessment does not affect the outcome in normal eyes. In fact, under mesopic and scotopic conditions, the luminance of the test field is so much higher than that of the room so that it determines the pupil size. Regardless of the lighting level, straylight measured in a laboratory, is valid for photopic pupils at an adaptation level corresponding with about 400 lux room illuminance.

Light scattering levels from intraocular lenses extracted from donor eyes.

PURPOSE: To assess light scatter levels of intraocular lenses (IOLs) extracted from donor eyes to understand straylight elevation documented earlier in pseudophakic population studies and identify potential sources of light scattering in IOLs. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Experimental study. METHODS: Light scattering in 74 donor IOLs was measured with the C-Quant device adapted for in vitro analysis of IOLs. Straylight was assessed at a 2.5-degree and 7.0-degree scatter angle, and results were compared with the straylight of a 20-year-old crystalline lens, a 70-year-old crystalline lens, and a lens with cataract. To identify potential changes to the IOL material, the IOLs were examined with a light microscope and a slitlamp. RESULTS: At 2.5 degrees and 7.0 degrees, the straylight parameter was 5.78 deg2/steradian (sr) ± 4.70 (SD) and 5.06 ± 4.01 deg2/sr, respectively. Forty-one percent of IOLs showed lower straylight than the 20-year-old lens. In 14%, the scattering intensity was higher than in the 70-year-old lens; none showed straylight comparable to that of the cataractous lens. Increased straylight was associated with surface deposits, snowflake-like degeneration, and glistenings. The incidence of IOL-related complications differed between the IOL groups. CONCLUSIONS: Microscopic structural alterations of IOLs play a major role in straylight elevations in pseudophakic eyes. A clear correlation with degeneration and/or alteration of implanted IOLs was found. Although these IOL-related complications would likely not affect visual acuity, they give rise to straylight and thus can cause disability glare and other symptoms.

Changes in Intraocular Straylight and Visual Acuity with Age in Cataracts of Different Morphologies.

PURPOSE: To investigate the significance of difference in straylight of cataract eyes with different morphologies, as a function of age and visual acuity. METHODS: A literature review to collect relevant papers on straylight, age, and visual acuity of three common cataract morphologies leads to including five eligible papers for the analysis. The effect of morphology was incorporated to categorize straylight dependency on the two variables. We also determined the amount of progression in a cataract group using a control group. RESULTS: The mean straylight was 1.22 log units ± 0.20 (SD) in nuclear (592 eyes), 1.26 log units ± 0.23 in cortical (776 eyes), and 1.48 log units ± 0.34 in posterior subcapsular (75 eyes) groups. The slope of straylight-age relationship was 0.009 (R2 = 0.20) in nuclear, 0.012 (R2 = 0.22) in cortical, and 0.014 (R2 = 0.11) in posterior subcapsular groups. The slope of straylight-visual acuity relationship was 0.62 (R2 = 0.25) in nuclear, 0.33 (R2 = 0.13) in cortical, and 1.03 (R2 = 0.34) in posterior subcapsular groups. CONCLUSION: Considering morphology of cataract provides a better insight in assessing visual functions of cataract eyes, in posterior subcapsular cataract, particularly, in spite of notable elevated straylight, visual acuity might not manifest severe loss.

Validation of a spectral light scattering method to differentiate large from small particles in intraocular lenses.

A psychophysical approach has been designed to measure straylight from intraocular lenses (IOLs) in vitro. This approach uses a clinical straylight meter (C-Quant) and an observer's eye as optical detector. Based on this, we introduced a method for study of straylight-wavelength dependency for IOLs. This dependency can be used to distinguish between 2 types of scattering particles (small and large) as defined by Mie theory. Validation was performed using a turbidity standard and scattering filters. Several IOLs were analyzed to identify potential scattering sources. Large particles were found to predominate in scattering from the studied lenses. This was confirmed by straylight-angular dependency found in these IOLs.

Straylight from glistenings in intraocular lenses: In vitro study.

PURPOSE: To assess light scattering from intraocular lenses (IOLs) with different numbers of laboratory-induced glistenings and create a model for predicting glistening effects on straylight. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Experimental study. METHODS: Glistenings were induced in 7 Acrysof IOLs using an accelerated aging method. To create different numbers of glistenings, the IOLs were immersed in a balanced salt solution at temperatures ranging from 37°C to 60°C and cooled to room temperature. The glistenings were analyzed with a microscope. Light scattering from the IOLs was assessed using a commercial straylight meter (C-Quant) adapted for in vitro evaluation of IOLs at a 2.5-degree and 7.0-degree scatter angle. A model was proposed relating straylight increase to the total number and surface portion (total number × area) of glistenings. Results were compared to the Mie theory. RESULTS: The number of induced glistenings ranged from 114 to 12 386 per mm2, and the surface portion ranged from 1.4% to 26.9%. At 2.5 degrees, the range in the straylight parameter was 1.49 to 72.49 deg2/steradian (sr); at 7.0 degrees, it was 1.72 to 62.87 deg2/sr. Straylight was proportionally related to the total number of glistenings (0.0046 × total number) (R2 = 0.96) and the surface portion (217 × surface portion) (R2 = 0.97). The measurements agreed well with Mie theory. CONCLUSIONS: Straylight from glistenings in IOLs had an accurate proportional association with their total number and surface portion. The proposed model proved effective in predicting straylight from glistenings. Numerous glistenings are needed to cause significant straylight elevation.

Validation, test-retest reliability and norm scores for the Dutch Catquest-9SF.

PURPOSE: The Catquest-9SF questionnaire is a unidimensional, reliable, valid and short patient-reported outcome measure for quantifying benefits in visual functioning from cataract surgery. Our aim was to develop a formal Dutch translation, calculate norm scores, assess its validity and test-retest reliability and provide an easy way for use in clinical practice. METHODS: Translation of the questionnaire was performed according to guidelines of the International Society for Pharmacoeconomics and Outcomes Research. Catquest-9SF was obtained in 657 patients pre- and postcataract surgery. We applied Rasch and classical analyses to determine the questionnaire performance with characteristics such as unidimensionality, reliability, separation and differential item functioning. Test-retest reliability was assessed in another group of 145 patients. A cut-off value to discriminate between people with and without cataract, norm scores and a reliable change index (RCI) were calculated using data from a sample of 916 'healthy' persons from the normal population. RESULTS: The Dutch Catquest-9SF was unidimensional, and both person and item reliability were high; 0.87 and 0.99, respectively. Cronbach's alpha was 0.94, test-retest reliability was 0.85 and the intraclass correlation coefficient was 0.93. Catquest-9SF showed to be responsive to the effect of cataract surgery (effect size = 1.27; p < 0.001). The cut-off value was -1.90, and RCI was 2.27. A quick-access table with norm scores and percentiles was established to facilitate clinical interpretation. CONCLUSION: This investigation provides validity and reliability of the Dutch Catquest-9SF as well as norm scores and a new tool to facilitate the clinical interpretation of patient scores. This makes Catquest-9SF suitable for routine use in clinical practice.

Straylight as an Indicator for Cataract Extraction in Patients with Retinal Dystrophy.

PURPOSE: Straylight reduces retinal sensitivity, which is particularly relevant in conditions with retinal dysfunction, such as retinitis pigmentosa (RP). Retinitis pigmentosa is associated with posterior subcapsular cataract (PSC), a cataract type that is known to cause severe disability glare (i.e., straylight). Study purposes were (1) to determine the severity of disability glare before and after cataract extraction (CE) in subjects with retinal dystrophy; (2) to study possible aggravation of disability glare due to the combination of retinal degradation and increased straylight from PSC; and (3) to evaluate whether straylight can be used to support the possible benefit of (early) CE. DESIGN: Prospective, comparative study. PARTICIPANTS: Sixteen patients (25 eyes) with retinal dystrophy scheduled for CE participated. METHODS: Cataract severity was graded according to the Lens Opacities Classification System (LOCS) III. Preoperatively and postoperatively, corrected distance visual acuity (CDVA), spatial contrast sensitivity with the Pelli-Robson chart, and straylight were tested. Retinal function was assessed with Goldmann visual field and temporal contrast sensitivity (TCS). Temporal contrast sensitivity is a flicker test to evaluate central retinal sensitivity isolated from the eye's optical quality. Central retinal structure was assessed with spectral-domain OCT and fundus autofluorescence. MAIN OUTCOME MEASURES: Preoperative and postoperative straylight were measured using the C-Quant (Oculus Optikgeräte GmbH, Wetzlar, Germany) and expressed as the logarithm of the straylight parameter s: log(s). RESULTS: The average straylight value was 1.75 preoperatively and 1.45 postoperatively, 7.1 and 3.5 times higher than in a healthy young eye, respectively. Functionally significant improvement, defined as >0.20 log, was found in 72% of eyes for straylight and in 20% of eyes for CDVA. The CDVA and TCS were significantly correlated. Only straylight improvement was related to preoperative values; therefore, straylight was the only parameter that could be used to support postoperative improvement. In retinal dystrophy, eyes with cataract and a preoperative straylight value ≥1.66 log(s), a 50% chance of functionally significant log(s) improvement can be expected. CONCLUSIONS: In patients with retinal dystrophy, straylight caused by cataract substantially aggravates visual disability, whereas CDVA is less affected. Therefore, straylight is a valuable (additional) indicator for beneficial CE in patients with retinal dystrophy and cataract.

Accuracy of Total Corneal Astigmatism Measurements With a Scheimpflug Imager and a Color Light-Emitting Diode Corneal Topographer.

PURPOSE: To determine the accuracy of total corneal astigmatism measurements with a Scheimpflug imager and a color light-emitting diode corneal topographer, and to compare the accuracy of total corneal astigmatism measurements with the accuracy of measurements that are based only on the anterior corneal surface. DESIGN: Prospective validity assessment. METHODS: This study was conducted at the Rotterdam Ophthalmic Institute, Rotterdam, Netherlands. The study population consisted of 91 eyes of 91 patients with monofocal, non-toric intraocular lenses (IOLs). Refractive astigmatism was measured with the ARK-530A autorefractor (Nidek, Gamagori, Japan). Anterior and total corneal astigmatism were measured with the Pentacam HR (Oculus, Wetzlar, Germany) and the Cassini (i-Optics, The Hague, Netherlands). Under the assumption that refractive astigmatism must equal total corneal astigmatism in these patients, accuracy of the corneal astigmatism measurements was defined as the vectorial difference with the refractive astigmatism, with lower vector differences denoting higher accuracy. RESULTS: The median refractive astigmatic magnitude was 0.84 diopter (D). The mean difference vector lengths were 0.61 D, 0.58 D, 0.49 D, and 0.45 D for Pentacam anterior, Cassini anterior, Pentacam total, and Cassini total corneal astigmatism, respectively. The mean difference vector length decreased by 0.12 and 0.13 D for Pentacam and Cassini, respectively, if the total instead of anterior corneal astigmatism was measured. These decreases were statistically significant (P < .001). CONCLUSIONS: With Pentacam as well as with Cassini, the accuracy of total corneal astigmatism measurements was higher than that of anterior corneal astigmatism measurements. Measuring total instead of anterior corneal astigmatism may therefore decrease the residual astigmatism in toric IOL implantation.

Comparison of ocular straylight after implantation of multifocal intraocular lenses.

UNLABELLED: A comprehensive review of the effect of multifocal intraocular lens (IOL) designs on postoperative ocular straylight was performed. Studies reporting straylight values obtained with the natural pupil using the C-Quant device after uneventful multifocal IOL implantation were included. The IOLs were categorized based on their material characteristics; that is, hydrophobicity and presence of colored chromophores. Age adjustment was achieved using the straylight age-dependency norm for pseudophakic eyes. This norm also served as a reference for comparing mean straylight levels of the various IOLs. The literature review identified 10 studies reporting 9 multifocal IOL designs. The hydrophilic IOLs showed less straylight than the hydrophobic IOLs by 0.08 log(s) (P = .001). Blue violet light-filtering IOLs showed less straylight than standard IOLs by 0.04 log(s), which was not statistically significant (P = .32). Hydrophobicity was a factor that significantly affected straylight in multifocal IOLs. FINANCIAL DISCLOSURES: The Netherlands Academy of Arts and Sciences owns a patent on straylight measurement, with Dr. van den Berg as the inventor, and licenses it to Oculus Optikgeräte GmbH for the C-Quant instrument. No other author has a financial or proprietary interest in any material or method mentioned.

Long-term changes in intraocular lens position and corneal curvature after cataract surgery and their effect on refraction.

PURPOSE: To evaluate the role of intraocular lens (IOL) position shift and changes in corneal curvature on long-term refractive shift after cataract surgery. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Prospective cohort study. METHODS: Patients who had routine cataract surgery with implantation of a hydrophobic acrylic 1-piece IOL (Acrysof SA60AT) in the capsular bag were enrolled. Measurements were performed preoperatively and 1 month, 3 months, and 1 year postoperatively. Refraction was measured with the ARK-530A autorefractor. The IOL position and corneal curvature were measured with the Lenstar LS-900 biometer. The refractive effect of changes in IOL position and corneal curvature was calculated with a Gaussian optics-based thin-lens formula and correlated with the measured refractive shift. RESULTS: The study group comprised 59 eyes of 59 patients. The median measured absolute refractive change was 0.25 diopter (D). The IOL position showed a statistically significant mean posterior shift of 0.033 mm ± 0.060 (SD) between 1 month and 1 year postoperatively (P < .01), of which the median calculated absolute refractive effect was 0.05 D. This did not correlate with the measured refractive shift (Pearson r = 0.10, P = .46). Natural fluctuations in corneal curvature caused a median calculated absolute refractive effect of 0.17 D, which correlated well with the measured refractive shift (Pearson r = .55, P < .001). CONCLUSIONS: Long-term changes in refraction after cataract surgery resulted from natural fluctuations in corneal curvature rather than from IOL position shift. These fluctuations limit the accuracy with which the refractive outcome can be planned. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Value of posterior keratometry in the assessment of surgically induced astigmatic change in cataract surgery.

PURPOSE: To investigate the value of posterior keratometry in the assessment of surgically induced astigmatic change (AC) in cataract surgery, with particular emphasis on the influence of test-retest variability. METHODS: Seventy-seven eyes of 77 cataract patients scheduled for routine cataract surgery were enrolled. All patients received a 2.2-mm self-sealing scleral incision (n = 24), single-plane clear corneal incision (SPCCI; n = 29) or biplanar clear corneal incision (BPCCI; n = 24). Measurements of anterior and posterior corneal astigmatism were performed with a rotating Scheimpflug camera (Pentacam HR) preoperatively and postoperatively. Two repeated readings were taken preoperatively to assess the role of the test-retest effect. Astigmatic change (AC) was analysed according to the polar value method. RESULTS: On the anterior corneal surface, SPCCIs and BPCCIs caused a statistically significant mean flattening of the incisional meridian of 0.37 and 0.27 dioptres (D), respectively. Scleral incisions on average did not cause AC, although steepening, flattening or torque beyond the test-retest effect was observed in individual cases. On the posterior surface, mean power changes in the incisional meridian were below 0.1 D for all incisions, and these changes were of the same order of magnitude as the test-retest effect. CONCLUSION: Surgically induced AC of the posterior corneal surface after cataract surgery is of negligible clinical relevance. Moreover, it is of the same order of magnitude as the test-retest variability of the measurement device and therefore cannot (yet) be reliably assessed.

Ocular straylight in the normal pseudophakic eye.

PURPOSE: To assess normal values for straylight in the pseudophakic eye as a function of age and to develop a model to predict the improvement in straylight after lens extraction based on preoperative straylight levels. SETTING: Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands. DESIGN: Review with retrospective cross-study analysis. METHODS: A literature review was performed to identify relevant papers on straylight and pseudophakia with no patient comorbidities. Sixteen papers met the eligibility criteria and were included in the analysis. The postoperative results were used to define the norm for straylight in pseudophakia. Straylight improvement after lens replacement was assessed by evaluation of preoperative and postoperative values. The age effect was incorporated to determine a model for straylight improvement. RESULTS: The mean postoperative straylight value derived from 16 studies (1869 eyes) was 1.21 log units ± 0.21 (SD). Age dependence could be assessed from 13 studies (1533 eyes), resulting in the straylight age-norm curve in pseudophakic eyes as follows: Straylight value = 0.0044 × age + 0.89 with ± 0.42 log units of 95% confidence interval. A strong correlation was observed between preoperative straylight and its improvement after lens extraction, yielding the following relationship: Straylight improvement = 1.04 × preoperative straylight value - 0.006 × age - 0.84. CONCLUSION: A norm for straylight in the pseudophakic eye was developed that is considerably different from the previously published norm for the phakic eye. The new pseudophakic norm can be used clinically to predict the straylight value after lens replacement and as a reference criterion for clinical studies. FINANCIAL DISCLOSURE: The Netherlands Academy of Arts and Sciences owns a patent on straylight measurement, with Dr. van den Berg as the inventor, and licenses that to Oculus Optikgeräte GmbH for the C-Quant instrument. No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of keratometry with a novel Color-LED corneal topographer.

PURPOSE: To assess the performance of a novel keratometer based on reflections of colored light-emitting diodes (LEDs) and compare it with devices based on Placido rings, monochromatic LEDs, and Scheimpflug images. METHODS: Sixty-three eyes of 63 patients with virgin corneas underwent keratometry with color-LED corneal topography (Cassini; i-Optics, The Hague, The Netherlands) and with devices based on Placido ring reflections (Keratron; Optikon, Rome, Italy), monochromatic LED reflections (Lenstar; Haag-Streit, Koeniz, Switzerland), and Scheimpflug imaging (Pentacam; Oculus Optikgeräte, Wetzlar, Germany). Three repeated measurements were performed with each device. Comparability and repeatability of corneal power and cylinder measurements were assessed. The Bonferroni-corrected α-threshold for statistical significance was 0.016. RESULTS: Corneal power measurements with the Cassini topographer were not statistically significantly different from those with the Pentacam (P = .64). They were statistically significantly lower than those with the Keratron and Lenstar (P < .01), but the differences were of negligible clinical relevance. Cylinder measurements with the Cassini topographer were not statistically significantly different from those with any other device (P = .46). Repeatability of Cassini corneal power measurements was not statistically significantly different from that of the Keratron (P = .02), but was statistically significantly lower than that of the Lenstar and Pentacam (P < .001). Repeatability of Cassini cylinder measurements was statistically significantly higher than that of the Pentacam and Keratron (P < .001), but was not statistically significantly different from that of the Lenstar (P > .05). CONCLUSIONS: Corneal power and cylinder measurements with color-LED corneal topography yielded values that were comparable to those of other commonly used devices. Repeatability of corneal power measurements was lower compared to some devices, but repeatability of cylinder measurements was relatively high. This may be of particular interest when using toric intraocular lenses.