Burst-shot infrared digital photography to determine scotopic pupil diameter

PURPOSE: To evaluate the usefulness of infrared digital photography for determining scotopic pupil size by comparing infrared digital photography with a Colvard pupillometer (Oasis Medical). SETTING: Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea. METHODS: Scotopic pupil size in 50 eyes of 25 healthy individuals was measured with a Colvard pupillometer and a digital camera (DSC-F828) using infrared burst shots after 5 minutes of dark adaptation. Measurements were performed by 2 independent examiners (E1 and E2). The digital photograph images were read using the ruler function of Adobe Photoshop 7.0 by 2 independent readers (R1 and R2). Agreement and repeatability were analyzed using the comparison method described by Bland and Altman. RESULTS: The mean scotopic pupil diameter measured using the Colvard pupillometer was 6.69 mm +/- 0.78 (SD) (E1) and 6.70 +/- 0.71 mm (E2). The mean scotopic pupil diameter measured from the digital photograph images was 6.67 +/- 0.75 mm (E1) and 6.66 +/- 0.78 mm (E2). The mean difference between E1 and E2 with both devices was small; however, the result with the infrared digital camera was marginally smaller than with the Colvard pupillometer. The limits of agreement were -0.01 +/- 0.70 mm with the Colvard pupillometer and 0.01 +/- 0.20 mm with the digital photograph image. The digital photograph image showed better agreement. The coefficient of interrater repeatability was smaller for the digital photograph image (0.39) than for the Colvard pupillometer (0.70). CONCLUSIONS: Scotopic pupil measurement using an infrared digital camera with a burst shot had good agreement with the Colvard pupillometer and better repeatability. The infrared digital camera is less expensive, and pupil unrest can be overcome by taking serial images.     

Correlation of infrared pupillometers and CCD-camera imaging from aberrometry and videokeratography for determining scotopic pupil size

PURPOSE: To compare 2 infrared pupillometers with a videokeratographer and 2 aberrometers for the determination of scotopic pupil size. SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: The pupil diameter was measured in 100 eyes of 51 patients after 2 minutes of dark adaptation using the following devices: digital infrared pupillometer (Procyon Instruments Ltd.), handheld infrared pupillometer (Colvard) (Oasis Medical), Zywave aberrometer (Bausch & Lomb), Wasca aberrometer (Asclepion-Meditec-Zeiss), and Orbscan II topography system (Bausch & Lomb Surgical). Measurements taken with the Procyon pupillometer were considered reference values for comparison with the other devices. Statistical evaluation was performed using the Bland-Altmann method for comparison of measurement techniques. RESULTS: The mean pupil size was 6.10 mm +/- 0.86 (SD) with the Procyon pupillometer, 5.68 +/- 1.07 mm with the Colvard pupillometer, 5.91 +/- 1.01 mm with the Zywave aberrometer with the fixating target turned off, 5.09 +/- 1.14 mm with the Zywave aberrometer with the fixating target turned on, 5.59 +/- 0.99 mm with the Wasca aberrometer, and 3.75 +/- 0.67 mm with the Orbscan topographer. The limits of agreement were smallest for measurements between Procyon and Colvard and largest for measurements between Procyon and Orbscan. The sign test revealed statistically significant differences for all devices compared with the Procyon pupillometer (P<.001 in all cases) except the Zywave aberrometer with the fixating target turned off (P=.13). CONCLUSIONS: The Zywave wavefront sensor with the fixating target turned off using the study settings and light conditions provided measurements of scotopic pupil diameter that were closest to the reference values (Procyon). With the other devices (Colvard pupillometer, Zywave aberrometer with the fixating target switched on, Wasca aberrometer, and Orbscan topographer), the difference was statistically significant.     

Scotopic measurement of normal pupils: Colvard versus Video Vision Analyzer infrared pupillometer

PURPOSE: To prospectively measure the scotopic pupil diameter in a normal population and to compare 2 infrared pupillometers for these measurements. SETTING: Johann Wolfgang Goethe-University, Department of Ophthalmology, Frankfurt am Main, Germany. METHODS: The Colvard infrared pupillometer was compared to the Video Vision Analyzer (VIVA) infrared pupillometer under scotopic light conditions in 33 participants (aged 19 to 55 years). Reliability was assessed by 2 independent examiners (E1, E2). Statistical analysis was performed using a comparison method by Bland and Altman. RESULTS: Mean pupil diameter was 6.16 mm +/- 1.20 (SD) (range 3.20 to 9.00 mm) with all measurements taken under scotopic illumination. The mean scotopic pupil diameter was 6.08 +/- 1.16 mm (range 3.2 to 8.4 mm) with the Colvard pupillometer and 6.24 +/- 1.28 mm (3.5 to 9.0 mm) with the VIVA pupillometer. The mean differences between the Colvard and VIVA were -0.27 mm (E1) and -0.05 mm (E2). Limits of agreement ranged from 1.4 (Colvard) to 2.4 (VIVA). The coefficients of repeatability ranged from 0.7 (Colvard) to 1.1 (VIVA). CONCLUSIONS: A mean scotopic pupil diameter of 6.15 mm with a maximal pupil size of 9.00 mm can be expected in a normal population; this should be considered in refractive corneal and refractive lens surgery. Measurements with the Colvard pupillometer were more reliable and precise than those with the VIVA pupillometer.     

Comparison of dynamic digital pupillometry and static measurements of pupil size in determining scotopic pupil size before refractive surgery

PURPOSE: To compare 2 digital infrared pupillometers. SETTING: Anterior Segment Service, Moorfields Eye Hospital, London, England. METHODS: Eighty-eight eyes of 44 healthy subjects were recruited into the study. The scotopic pupil size was measured with 2 instruments, a digital pupillometer (Procyon) and a Hartman-Shack wavefront aberrometer (Visx WaveScan). Agreement between the instruments was assessed. RESULTS: There were 21 men and 23 women with a mean age 38.1 years +/- 9.2 (SD) (range 23 to 62 years). The mean scotopic pupil diameter was significantly larger with the WaveScan (6.61 +/- 0.92 mm) than with the Procyon pupillometer (6.40 +/- 0.90 mm), P<.001. CONCLUSIONS: There was good agreement in measurement of scotopic pupil size between the two instruments. The larger pupil diameter found with the Visx WaveScan than with the Procyon digital pupillometer probably represents the different illumination level used by each instrument, the effects of accommodation, and target fogging.     

Comparison of 2 multiple-measurement infrared pupillometers to determine scotopic pupil diameter

PURPOSE: To compare a monocular and a binocular multiple-measurement digital infrared pupillometers for measuring scotopic pupil diameter. SETTING: Department of Ophthalmology, Loma Linda University, Loma Linda, California, USA. METHODS: Scotopic pupil size was measured after 1 minute of dark adaptation in 42 eyes of 21 volunteers. Measurements were taken twice each with 2 multiple-measurement digital infrared pupillometers, the monocular pupillometer (Neuroptics, Inc.), and the binocular pupillometer (P2000D, Procyon, Ltd.) Intraclass correlation coefficients (ICC) and limits of agreement (LOA) were used to measure repeatability and agreement of measures with each instrument and between instruments. The Wilcoxon signed rank test was used to compare variability of measurements within each instrument. RESULTS: The mean scotopic pupil size was 4.79 mm +/- 0.95 (SD) with the Procyon and 4.86 +/- 0.93 mm with the Neuroptics. Repeatability and agreement tests for the Procyon measures showed the following: ICC, 0.954; 95% confidence interval (CI), 0.916-0.975; LOA, -0.60 to 0.56; range, 1.16. The Wilcoxon signed rank test of variability gave a Z score of -2.53 (P = .01, 2 tailed). The repeated measures testing with the Neuroptics pupillometer showed the following: ICC, 0.985; 95% CI, 0.972-0.992; LOA, -0.39 to 0.26; range, 0.64; Z score, -1.15 (P = .25, 2-tailed). Repeatability and agreement tests for measures between instruments showed the following: ICC, 0.954; 95% CI, 0.916-0.975; LOA, -0.60 to 0.50; range 1.11. CONCLUSIONS: There was a high repeatability and agreement in scotopic pupil diameter for repeated measures within each device and measurements between the devices. Differences in variability in scotopic pupil diameter evaluated by the Wilcoxon signed rank test were significant only with the Procyon pupillometer.     

Comparison of different methods for pupillometry for mesopic and scotopic conditions

BACKGROUND: The aim of the study was to compare different methods for pupillometry, namely the Goldmann perimeter (gp), the Colvard pupillometer (cp) and the Procyon Video pupillometer (pvp). For the pvp three different illuminations were available: mesopic high, mesopic low, and scotopic. PATIENTS: The size of the pupil was measured in 100 eyes (50 healthy subjects) with the three different methods. We examined 29 females (58 %) and 21 males (42 %) with an average age of 25.16 years, ranging from 18 to 30 years. RESULTS: For the Goldmann perimeter, a mean pupil diameter of 4.39 mm +/- 0.62 mm was found under mesopic conditions (1.40 lux). For the Colvard pupillometer for scotopic conditions (0 lux), a mean pupil diameter of 6.80 mm +/- 0.81 mm was found. For pvp the pupil diameter ranged from 7.06 mm +/- 0.71 mm for scotopic (0.04 lux), over 6.24 mm +/- 0.80 mm for mesopic low (0.40 lux) to 4.65 mm +/- 0.73 mm for mesopic high conditions (4.00 lux). CONCLUSION: The comparison of the results showed a high correlation between the Goldmann perimeter and the Procyon Video Pupillometer for mesopic high with a minimum difference of 0.25 +/- 0.69 mm. By addition of 2.67 mm to the mesopic measurement of the Goldmann perimeter, the results for the Procyon Video pupillometer at the scotopic level, by addition of 2.4 mm the scotopic measurement of the Colvard pupillometer could be achieved.     

Evaluation of pupil dynamics after implantation of artisan phakic intraocular lenses

PURPOSE: To compare pre- and postoperative horizontal and vertical pupil diameters after horizontal Artisan phakic intraocular lens (PIOL) (Ophtec BV, Groningen, The Netherlands) implantation for correction of myopia. METHODS: The pre- and postoperative scotopic pupil diameters measured by the Colvard pupillometer (Oasis Medical, Glendora, Calif) were compared in 71 eyes after Artisan PIOL implantation (Artisan Colvard group). Analysis of pupil shape (vertical vs horizontal diameter, V/H ratio) after horizontal Artisan PIOL implantation was performed with the Procyon pupillometer (Procyon Instruments Ltd, London, United Kingdom) in 121 eyes (Artisan Procyon group) under scotopic, mesopic-low, and mesopic-high conditions and compared to an age- and refraction-matched control group of 121 eyes of refractive surgery candidates (Procyon control group). RESULTS: After horizontal Artisan PIOL implantation, the mean horizontal pupil diameter decreased from 6.231 +/- 0.70 mm preoperatively to 5.34 +/- 0.68 mm postoperatively in the Artisan Colvard group (P < .01). The mean horizontal scotopic diameter was 5.60 +/- 0.66 mm, the mesopic-low diameter was 4.94 +/- 0.71 mm, and the mesopic-high diameter was 3.98 +/- 0.54 mm for the Artisan Procyon group. The mean horizontal scotopic diameter was 6.29 +/- 0.91 mm, the mesopic-low diameter was 5.40 +/- 0.96 mm, and the mesopic-high diameter was 4.16 +/- 0.80 mm in the Procyon control group. A significant increase was noted in V/H ratio under scotopic, mesopic-low, and mesopic-high conditions from 1.02, 1.02, and 1.01, respectively, in the Procyon control group to 1.17, 1.12, and 1.06, respectively, in the Artisan Procyon group (P < .01). CONCLUSIONS: Horizontal pupil size was significantly decreased after horizontal Artisan PIOL implantation and might be attributed to a mechanical restriction of the iris in the horizontal meridian.     

Comparison of the Colvard pupillometer and the Zywave for measuring scotopic pupil diameter

PURPOSE: To evaluate the accuracy and repeatability of two pupillometers. METHODS: Two pupillometers, the Colvard and Zywave, were used to measure scotopic pupil diameter for 64 consecutive patients. Accuracy and repeatability were assessed by two independent examiners and statistical analysis was performed using the comparison method described by Bland and Altman. RESULTS: Mean scotopic pupil diameter was 5.96 +/- 0.69 mm with the Colvard pupillometer and 5.77 +/- 0.85 mm with the Zywave. The difference between the Colvard and Zywave measurements was 0.21 +/- 0.56 mm (P < .001). The coefficient of interrater repeatability was smaller for the Colvard (0.59) than for the Zywave (1.17). The mean difference between the pupillometers for each examiner was 0.17 +/- 0.47 mm (P < .01) for examiner 1 and 0.26 +/- 0.64 mm (P < .01) for examiner 2. CONCLUSIONS: Scotopic pupil diameter measured with the Zywave was statistically but not clinically significantly smaller than that measured with the Colvard pupillometer. The Zywave produced an inter-rater repeatability comparable to other devices although not as good as the Colvard pupillometer.     

Pupil measurement using the Colvard pupillometer and a standard pupil card with a cobalt blue filter penlight

PURPOSE: To compare scotopic pupil measurements obtained with a Colvard pupillometer with measurements taken with a printed pupil gauge and penlight with a cobalt blue filter attachment in mesopic and scotopic luminance. SETTING: The Illinois Eye Institute, Chicago, Illinois, USA. METHODS: Pupil measurements were taken of both eyes of 38 patients (76 eyes). Any subject presenting with anterior segment disease, fixed or dilated pupils, iris abnormalities, or a history of eye disease or eye trauma was excluded. At a mesopic luminance of 2.11 foot-candles, pupil measurements were taken with a Bernell pupil card and penlight with a cobalt blue filter attachment. At a scotopic luminance of less than 2.00 foot-candles, pupil measurements were taken with the Bernell card system and the Colvard pupillometer. RESULTS: In mesopic luminance, the mean pupil diameter was 5.17 mm (range 3.0 to 7.5 mm) with the Bernell card method. The mean difference between the Colvard in scotopic luminance and the Bernell card system in mesopic luminance was -0.04 mm (P = .0831). In scotopic luminance, the mean pupil diameter was 6.32 mm (range 4.0 to 8.0 mm) with the Bernell card method and 5.13 mm (range 3.0 to 7.5 mm) with the Colvard pupillometer, with a mean difference of -1.18 mm (P<.0001). The limits of agreement between the mesopic Bernell card system and the Colvard pupillometer were small (-0.32 to 0.24), whereas the limits of agreement between the scotopic measurements of both techniques were large (-2.18 to -0.18). CONCLUSIONS: Under both illuminance conditions, the Bernell card system with the cobalt filter measured a larger pupil size than the Colvard pupillometer. The measurement differences between the techniques were most pronounced at the lower illumination. The limits of agreement were larger under the lower illumination, indicating more variation between techniques. This study suggests that the Bernell card system with cobalt illumination provides a generous measurement of the pupil size compared with the Colvard pupillometer, which makes it an appropriate and cost-effective screening tool for refractive surgery evaluation.     

Comparison of the pupil card and pupillometer in measuring pupil size

PURPOSE: To determine the difference in pupil size measured with the Colvard pupillometer in mesopic and scotopic luminance and with the Rosenbaum pupil card in mesopic luminance between 2 examiners. SETTING: Michel Pop Clinics, Montreal, Quebec, Canada. METHODS: Two examiners used the Colvard pupillometer and the Rosenbaum card to measure pupil size in 58 eyes. The Colvard pupillometer was used in mesopic and scotopic light conditions. The Rosenbaum card was used in mesopic luminance only. Pupil size was evaluated with a 1.0 mm interval scale at the nearest half millimeter. RESULTS: For the 3 sets of data, the limits of agreement and coefficient of interrater repeatability were calculated and a 2 x 2 factorial analysis of variance was performed. Because of interexaminer bias, measurements done in mesopic luminance with the Rosenbaum card were not statistically different from those with the Colvard pupillometer in scotopic luminance, although interrater repeatability of the Colvard pupillometer (0.8 mm) was superior to that of the Rosenbaum card (1.3 mm). CONCLUSIONS: Examiner bias was the greatest statistical bias in all sets of measures. Surgeons may want to opt for a "safe" limit of pupil size (ie, 0.5 to 0.8 mm greater than the measured size) when calculating optical zones in refractive surgery. Future devices for pupil measurement should be based on automatic adjustment sizing.     

Colvard pupillometer measurement of scotopic pupil diameter in emmetropes and myopes

PURPOSE: To prospectively compare the scotopic pupil size between emmetropes and myopes using a Colvard pupillometer. METHODS: The pupil diameters of 55 normal subjects and 55 healthy myopic subjects were measured with the Colvard pupillometer in a low-light situation that simulated the level of light encountered while driving at night. RESULTS: The mean (+/- SD) age of the emmetropic subjects was 30.78 years +/- 10.03 (range, 18-54 years) and the mean (+/- SD) age of the myopic subjects was 27.35 years +/- 8.43 (range, 21-52 years). The mean (+/- SD) scotopic pupil diameter was 6.46 +/- 0.90 mm (range, 4.5-8.0 mm) in the emmetropic group and 6.98 +/- 0.67 mm (5.5-8.5 mm) in the myopic group. The unpaired Student t-test showed that the difference in the scotopic pupil diameter between emmetropes and myopes was statistically significant (P =.0001). CONCLUSIONS: The mean scotopic pupil diameter in myopes was larger than that in emmetropes. Therefore, a large ablation zone of the cornea or an appropriate optical size of the phakic intraocular lens should be considered in refractive surgery. Preoperative scotopic pupil measurements may be necessary in all refractive patients.     

Inter- and intraobserver reliability of pupil diameter measurement during 24 hours using the Colvard pupillometer

PURPOSE: To evaluate the inter- and intraobserver agreement of pupil size diameter measurements determined using the Colvard pupillometer. METHODS: The eyes of 69 patients were examined (T1) using the Colvard pupillometer under mesopic and scotopic conditions by two examiners and repeated 1 hour (T2) and 24 hours (T3) later. The limits of agreement (mean difference between measurements +/- 2 standard deviations) were calculated for measurements between examiners (inter-examiner agreement) and between different time points measured by the same examiner (intra-examiner agreement). RESULTS: At T1, there was a 99% and a 97% chance of two different examiners producing readings within 0.5 mm under mesopic and scotopic conditions, respectively. There was a 15% chance and a 9% chance of finding a pupil difference > 0.5 mm over 1 hour under mesopic and scotopic conditions, respectively. For mesopic and scotopic measurements taken 24 hours apart, there was a 31% chance and a 21% chance, respectively, of finding a difference > 0.5 mm by the same examiner. CONCLUSIONS: This study showed high interobserver agreement under scotopic conditions, with 98% of measurements between two examiners falling within 0.5 mm, but substantial variability in pupil diameter measurements over 24 hours. These results suggest that serial office measurements may be necessary to establish the true range of pupil size.     

Scotopic pupil size in a normal pediatric population using infrared pupillometry

Purpose To determine scotopic pupil diameter in a normal pediatric population.Methods Scotopic pupil size was measured in 166 eyes of 83 children with a mean age of 6.01±4.11 years (range 0.51–14.26 years) using the light and hand-held Colvard infrared pupillometer. Measurements were performed under dim illumination after 2 min of dark adaptation. The Colvard infrared pupillometer utilizes light amplification technology to determine scotopic pupil size.Results The mean scotopic pupil diameter was 6.06±0.95 mm (range 4.0–8.5 mm) in the right eyes (OD) and 6.11±1.02 mm (range 4.0–8.5 mm) in the left eyes (OS), and 6.09±0.98 mm (range 4.0–8.5 mm) for both eyes (OU). An increase in mean scotopic pupil size with age was detected, with a peak of 7.28±0.42 mm at the age of 10–11 years. The correlation coefficient for age and scotopic pupil diameter was 0.51 OU (OD 0.52, OS 0.51), and the correlation coefficient for objective refraction (spherical equivalent) and scotopic pupil diameter was 0.05 OU (OD 0.01, OS 0.08).Conclusions The scotopic pupil diameter in a pediatric population increases with age until the age of 11 years and then decreases again.Presented in part at the American Society of Cataract and Refractive Surgeons (ASCRS), Boston, USA, May 2000 and the Deutsche Ophthalmologische Gesellschaft (DOG), Berlin, Germany, September 2000The authors have no proprietary interest in any of the devices used in this study     

Estimation of pupil size by digital photography

PURPOSE: To evaluate a digital photography method of pupil size estimation over a broad range of illumination conditions and to compare this method with common clinical techniques. SETTING: College of Optometry, Ohio State University, Columbus, Ohio, USA. METHODS: Two examiners measured the pupil diameter in 45 right eyes at 3 illumination levels: <0.63 lux (dark), 5 lux (dim), and 1000 lux (bright). Estimation by infrared video recording, the reference standard, was compared with measurements by digital photography, ruler, semicircular templates, and the Colvard pupillometer. Masked graders measured pupil size from infrared video recordings and digital photographs. RESULTS: The repeatability of the measurement method determined by the mean intraclass correlation coefficients was highest for video recording across conditions (0.86-0.97), followed by digital photography (0.76-0.94), Colvard pupillometry (0.63-0.82), ruler (0.71-0.85), and templates (0.70-0.83). An analysis of variance showed a significant difference in pupil size by method (P<.001). All methods except digital photography estimated smaller pupil sizes under dark and dim illumination than infrared video measurements (all P<.01). Under bright illumination, the ruler measurements were significantly smaller (-0.15 mm) and the Colvard pupillometer measurements were greater (+0.30 mm) than the reference (P<.01). The 95% limits of agreement (LoA) between examiners were smallest for video measurements at all light levels. The remaining measures ranked from best to worst by 95% LoA were digital photography, Colvard pupillometry, ruler, and templates. CONCLUSIONS: Estimation of pupil size by digital photography was more repeatable and accurate than estimates by common clinical techniques over a wide range of illumination. Although not as quick as other methods, digital photography is relatively inexpensive, permits lasting documentation, and allows independent grading suitable for clinical research purposes.     

Pupil size in refractive surgery candidates

PURPOSE: To assess pupil size measurements obtained under scotopic and mesopic conditions with the Procyon pupillometer and under photopic conditions with the Humphrey videokeratographer. METHODS: The pupil sizes of 96 candidates for refractive surgery (192 eyes) were measured with the Procyon pupillometer PS2000 SA and the Humphrey Atlas 992 corneal topographer. Anisocoria and pupillary unrest were analyzed according to gender (two groups: 51 females and 45 males), age (five groups: 20 to 30 yr, 31 to 40 yr, 41 to 50 yr, 51 to 60 yr, older than 60 yr) and level of refraction (five groups: >-6.00 D SE, -6.00 to -3.00 D SE, -3.00 to 0 D SE, 0 to +2.50 D SE, +2.50 to +5.00 D SE). RESULTS: The median value of pupil diameter measured with the Procyon pupillometer at the scotopic (0.04 lux), mesopic-low (0.4 lux), and mesopic-high (4 lux) levels of illumination were 6.54+/-0.88 mm; 5.62+/-0.95 mm, and 4.09+/-0.76 mm, respectively. The median pupil size with the Humphrey topographer was 3.65+/-0.62 mm. Pupillary unrest was highest at the mesopic-high level of illumination, with a median value of 0.31+/-0.34 mm. Median pupil size measured with both instruments at all light levels dropped significantly after the fifth decade of life (P<.05, ANOVA). CONCLUSIONS: The Procyon pupillometer and Humphrey videokeratographer revealed an inverse correlation between the pupil size and the age, but no relationship with gender or level of refraction. The Procyon pupillometer provides an objective method for measuring pupil size at controlled light levels with a permanent printed record.     

The correlation of pupil size measured by Colvard pupillometer and Orbscan II

PURPOSE: To assess the correlation of pupil sizes measured under different illuminations by Colvard pupillometer and the Orbscan II system and to determine the factors that may influence pupil sizes. METHODS: The study comprised 162 eyes of 162 patients with a mean age of 34.6 +/- 10.6 years (range: 16 to 65 years). The photopic pupil sizes were measured with Orbscan II (363 lux). The high mesopic and low mesopic pupil sizes were measured by Colvard pupillometer under 60.5 and 0.15 lux of illumination, respectively. Spherical equivalent of the manifest refraction was used to evaluate its correlation with the pupil size. RESULTS: The mean sizes of low mesopic and high mesopic pupil measured by Colvard pupillometer were 6.08 +/- 0.68 mm and 4.80 +/- 0.79 mm, respectively. The mean pupil size measured by Orbscan II was 3.87 +/- 0.61 mm. The pupil sizes were negatively correlated with age, but not correlated with refractive error when using multiple linear regression. Low mesopic pupil sizes were only moderately correlated with pupil sizes measured by Orbscan II (low mesopic pupil size [mm] = 0.755 x Orbscan II pupil size [mml + 3.13, r = 0.67). If > 4.5-mm pupil size measured by Orbscan II is used as the cut-off value for detecting low mesopic pupil sizes > 6.5 mm, there will be a sensitivity of 48.15% and a specificity of 93.97%. CONCLUSIONS: Pupil sizes measured with the Orbscan II were only moderately correlated with low mesopic pupil sizes measured with Colvard pupillometer. The Orbscan II is not a preferred tool for estimating low mesopic pupil sizes.     

Comparison of Colvard pupillometer and infrared digital photography for measurement of the dark-adapted pupil diameter

PURPOSE: To investigate the accuracy of pupil diameter measurement using the Colvard pupillometer and to determine the learning curve for inexperienced examiners. SETTING: Texas Tech University Health Sciences Center, Lubbock, Texas, USA. METHODS: In this population study, subjects with normal pupillary behavior were tested by 1 of 2 investigators (examiner A, examiner B). After 5 minutes of dark adaptation at 1 lux, digital infrared pupil photography of the right eye was performed, followed by measurement of the horizontal pupil diameter and vertical pupil diameter with the Colvard pupillometer. The photographs were digitally analyzed to determine the horizontal and vertical pupil diameters. During phase I of the study, examiners were masked to the results of infrared pupil photography; during phase II, they reviewed the infrared pupil photography results after each testing session. Bland-Altman plots were created to detect measurement bias; results were graphed by subject test sequence to assess learning. A test difference of less than +/-0.5 mm was considered clinically acceptable. RESULTS: Fifty-nine subjects were tested in phase I, of whom 39 had adequate infrared pupil photography for analysis; 40 were tested in phase II, of whom 34 were included. The mean age of the analyzed subjects was 27 years (range 18 to 44 years). For all subjects, the infrared pupil photography median horizontal pupil diameter was 7.09 mm +/- 0.75 (SD) (range 5.44 to 8.79 mm); the median vertical pupil diameter was 7.22 +/- 0.79 mm (range 5.45 to 9.10 mm). Examiner A initially had a negative bias (Colvard pupillometer value less than infrared pupil photography value) for both horizontal and vertical pupil diameter measurements, which resolved during phase I after 23 subjects were tested; 18 of the final 19 subjects tested (11 phase I, 8 phase II) showed a test difference of less than 0.5 mm for all readings. The pupil diameter did not affect the bias. Examiner B had a strong positive bias that persisted throughout the study. Testing 26 subjects in 5 sessions during phase II did not improve the accuracy. During the final testing session, 3 of 8 subjects had a test difference of 0.5 mm or more in at least 1 dimension. The pupil diameter did not affect the bias. CONCLUSION: The Colvard pupillometer is susceptible to user errors causing unidirectional bias and seems to have a steep and variable learning curve.     

Effect of brimonidine tartrate 0.2% ophthalmic solution on pupil size

PURPOSE: To evaluate the effect of brimonidine tartrate 0.2% ophthalmic solution on pupil size under scotopic and photopic luminance conditions in persons considering laser refractive surgery. SETTING: Ophthalmic Health Center, Tel Aviv, Israel. METHODS: The pupil size was measured in 36 eyes of 36 participants under scotopic and photopic conditions using the Colvard pupillometer (Oasis Medical) before and after brimonidine tartrate drops were administered. The pupil size was subsequently measured after 30 minutes and 4 and 6 hours. RESULTS: No difference was found in pupil size before brimonidine tartrate instillation in eyes with light or dark irides. Before instillation, the mean photopic pupil size was 4.81 mm +/- 0.54 (SD) (range 4.0 to 6.0 mm). At 30 minutes, all pupils became miotic, with a mean size of 3.77 +/- 0.51 mm (range 3.0 to 5.0 mm) (P<.0001). After 6 hours, 27.8% of the pupils had returned to their previous size. Before brimonidine tartrate administration, the mean scotopic pupil size was 6.22 +/- 0.73 mm (range 5.0 to 8.0 mm). There was significant miosis to 4.57 +/- 0.84 mm (range 3.0 to 6.5 mm) (P<.0001) that continued for at least 6 hours. The miotic effect of brimonidine tartrate was stronger in eyes with light irides. CONCLUSIONS: Brimonidine tartrate caused significant miosis, especially under scotopic conditions, most likely from its alpha-2 adrenergic effect. Under photopic luminance conditions, the miotic effect was pronounced.     

Vermessung der skotopischen Pupille

PURPOSE: The aim of the study was to compare the accuracy and the reproducibility of scotopic pupil measurements using two different methods. PATIENTS AND METHODS: We developed a simple test to measure scotopic pupil diameters using a narrow slit of light through a green filter of the Haag-Streit slitlamp. A total of 100 eyes from 50 refractive surgery candidates were prospectively examined by 2 independent investigators using both the Colvard pupilometer (Oasis/USA) and Sekundo's slitlamp green light test. Results were compared using all pairwise multiple comparison procedures (Student-Newman-Keuls method, SigmaStat/Jandel Scientific). The mean age of the patients was 36.3 years with a male:female ratio of 16:34. The colour of the iris was considered blue for 36 individuals and brown for the remainder. RESULTS: Reproducibility: the right eye mean pupil diameter using Sekundo's method was 6.4 mm (+/-0.9) measured by both the first (Slit 1R) and the second (Slit 2R) investigator. The left eye mean pupil diameter was 6.5 mm (+/-1) (Slit 1L) and 6.35 mm (+/-1) (Slit 2L), respectively. The following measurements were obtained with the Colvard pupillometer: (Colv1R)=6.25+/-0.85 mm, (Colv2R)=5.99+/-1 mm, (Colv1L)=6.15+/-0.91 mm, (Colv2L)=6.05+/-0.9 mm. There were no statistically significant differences between the two investigators within the same method of examination. Comparability:The data of both investigators were combined to form 4 groups: (Slit R)=6.4+/-0.96 mm, (Slit L)=6.4+/-1 mm, (Colv R)=6.05+/-0.9 mm, (Colv L)=6.1+/-0.93 mm. There was a significant difference ( p=0.024) between the two methods for both right and left eyes. Particularly for large pupils, the slitlamp green light measurements were significantly higher (up to 0.35 mm) than those with Colvard's device. CONCLUSIONS: The slitlamp green light test provides similar reproducibility for the measurement of the scotopic pupil diameter as the commercially available Colvard pupilometer.