Natural Pupil Research Articles

Surgical approach to and morphology of visually significant persistent pupillary membranes.

To characterize the morphology of persistent pupillary membranes (PPMs) in pediatric patients and explore the corresponding surgical approaches. Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. Prospective observational study. Consecutive pediatric patients with PPMs who underwent surgery from April 2020 to July 2022 were included. PPM morphology was assessed and categorized according to its anatomic relationship with crystalline lens and distribution of iris strands. The surgical approaches for different morphologies of PPMs were described in detail. The visual outcome and operation-related complications were recorded. 31 eyes from 19 patients were included with the mean age of 7.2 years. 3 morphological variants of PPMs were observed: type I (51.6%, 16/31), a spider-like appearance and no adhesion to the anterior lens capsule (ALC); type II (38.7%, 12/31), a loose central adherence to the ALC and partially thick iris strands attached to the iris collarette; type III (9.7%, 3/31), a tight central adherence to the ALC and only silk-like iris strands. Surgeries were performed with a natural pupil size in type I, while dilated pupil in the other types. The adhesions between PPM and the ALC were separated by viscoelastic injection in type II and by discission needles in type III. The corrected distance visual acuity was significantly improved from 0.34 ± 0.18 logMAR preoperatively to 0.17 ± 0.09 logMAR postoperatively ( P < .001). No operation-related complications were observed during 9.5-month follow-up. PPMs were categorized into 3 types according to their different morphologies, which helped to determine the best surgical strategy.

Comparison of two objective methods for measuring postoperative toric intraocular lens orientation under the natural pupil.

To evaluate and compare the accuracy of iTrace and CASIA2 in measuring the postoperative orientation of toric intraocular lens (IOL) without mydriasis. Tianjin Medical University Eye Hospital, Tianjin, China. Prospective cohort study. Patients with SN6AT toric IOLs implanted after cataract surgery were enrolled. 1 month after surgery, the toric IOL orientation were measured by iTrace and CASIA2 in non-mydriatic, semi-dark conditions. Then, the toric axis was directly reviewed using the slit-lamp under full mydriasis. Axis measurement differences between each of the 2 devices and the slit-lamp, described as their relative differences (RDs), were calculated and compared. The percentage of RDs within 5 degrees, within 10 degrees and greater than 30 degrees were analyzed. 77 eyes of 70 patients were included. Generally, the mean toric axis measurement RDs of CASIA2 and iTrace were 9.24 ± 10.53 degrees and 13.89 ± 15.47 degrees respectively ( P = .04). For CASIA2 (72 eyes), 54.17% (39), 72.22% (52), and 4.17% (3) of eyes had RDs within 5 degrees, within 10 degrees and greater than 30 degrees, compared with 40.00% (28), 61.43% (43) and 12.86% (9) for iTrace (70 eyes). The 95% limits of agreements of CASIA2 with slit-lamp was narrower than that of iTrace with slit-lamp. The median RD of CASIA2 was significantly smaller in eyes with pupil ≥4 mm under dark condition compared with eyes with pupil <4 mm ( P = .03). CASIA2 demonstrates greater precision in measuring toric IOL orientation under non-mydriatic conditions compared with iTrace. Moreover, the accuracy of CASIA2 is enhanced in cases of pupil >4 mm.

Cone-isolation contrast sensitivity – do pupil and stimulus sizes matter?

ABSTRACT Clinical relevance Computer-based colour perception tests permit clinical assessment of cone-specific pathways, proving valuable for both identifying type and severity of hereditary colour vision deficiency and enhanced detection and monitoring of acquired colour deficiency from disease. Understanding the parameters that affect computer-based colour perception tests may enhance their veracity and clinical utility. Background Testing contrast sensitivity separately for the three cone systems enables a quantification of colour perception that can be clinically useful. This study evaluated the effects of pupil diameter and stimulus size on cone contrast sensitivity (CCS) assessed with the ColorDx (Konan Medical, Incorporated). Methods Forty subjects, aged 21–31 years, who met the inclusion criteria participated. The tested eye was randomised. Two Landolt C sizes (2.68 degrees, 6/194, “small”; 8.58 degrees, 6/619, “large”) were used, with one size and three chromaticities presented per block of trials. Stimulus presentation used the adaptive screening mode, sequentially determining contrast sensitivity for long-, medium-, and short-wavelength stimuli. Subjects were tested with their natural pupil size (range 4–5 mm diameter), then while viewing through a 2.5-mm artificial pupil. Parametric statistical tests were used for comparisons of performance across pupil size and stimulus size. Results Two-way within-subjects ANOVA indicates no interaction between pupil size and stimulus size for any of the three stimulus chromaticities. The main effect of stimulus size was significant for M-cone (F = 6.506, 2-tailed P = .015) and S-cone (F = 67.728, 2-tailed P < .001) stimuli. The main effect of pupil size was significant for all three stimulus chromaticities (L-cone: F = 227.161, M-cone: F = 249.979, S-cone: F = 89.371, 2-tailed P < .001 for all). Conclusion Although CCS was reduced for all three chromaticities and both stimulus sizes with lower retinal illuminance, only S-wavelength cone contrast sensitivity was significantly different for the small versus large stimuli under the 2.5-mm pupil condition in this cohort. Whether CCS in older patients with naturally small pupils changes with an enlarged stimulus or dilated pupils remains to be explored.

Retinal image quality in myopic children undergoing orthokeratology alone or combined with 0.01% atropine

BackgroundThe retinal image quality derived from lower-order (LOA) and higher-order aberrations (HOA) for fixed 3-mm and photopic pupil diameters, in children undergoing combined 0.01% atropine and orthokeratology (AOK) versus those receiving orthokeratology alone (OK) over two years was evaluated.MethodsThe visual Strehl ratio based on the optical transfer function (VSOTF), derived from 2nd- to 4th-order terms (LOA and HOA combined), 2nd-order terms (LOA only), and 3rd- to 4th-order terms (HOA only) for fixed 3-mm and natural photopic pupil diameters, was compared between the two treatment groups. The individual Zernike coefficients for a fixed 3-mm pupil size of 2nd- to 4th-orders, root mean square (RMS) of LOA ({Z}_{2}^{0}, {Z}_{2}^{-2}, and {Z}_{2}^{2} combined), HOA (3rd to 4th orders inclusive), and Coma ({Z}_{3}^{-1}{mathrm{and }Z}_{3}^{1} combined) were also compared between the two groups.ResultsRight eye data of 33 AOK and 35 OK participants were analysed. Under photopic conditions, significantly lower VSOTF based on HOA only was observed in the AOK group compared with that in the OK group at all post-treatment visits (all P < 0.05); however, interactions between HOA and LOA resulted in comparable overall retinal image quality (i.e., VSOTF based on LOA and HOA combined) between the two groups at all visits (all P > 0.05). For a fixed 3-mm pupil size, the VSOTF based on HOA only, LOA only, or HOA and LOA combined, were not different between the two groups (all P > 0.05). AOK participants had slower axial elongation (mean ± SD, 0.17 ± 0.19 mm vs. 0.35 ± 0.20 mm, P < 0.001), a larger photopic pupil size (4.05 ± 0.61 mm vs. 3.43 ± 0.41 mm, P < 0.001) than OK participants, over two years.ConclusionsHOA profile related to an enlarged pupil size may provide visual signal influencing eye growth in the AOK group.

Use of multifocal electroretinograms to determine stage of glaucoma.

To determine whether multifocal electroretinograms (mfERGs) recorded with natural pupils and skin electrodes can be used to determine the stage of open angle glaucoma (OAG). Two hundred eighteen eyes of 132 OAG patients and 62 eyes of 62 normal subjects whose best-corrected visual acuity (BCVA) was 0.1 logarithm of the minimum angle of resolution (logMAR) units (20/25) or less were studied. The mean deviations (MDs) obtained by Humphrey Visual Field Analyzer (HFA), optical coherence tomographic (OCT) images, and mfERGs were analyzed. The glaucoma was classified into 4 stages: preperimetric glaucoma (PPG), early stage, moderate stage, and advanced stage glaucoma. The parameters of the mfERGs examined were the amplitudes of the two positive peaks (P1, P2) of the second order kernels in the nasal and temporal fields within the central 15° diameter. The mean age of all participants (patients and normals) was 63.8 ± 10.8 years. With the progression of glaucoma, the amplitudes of P1 in the nasal hemifield increased and the amplitudes of P2 decreased. The nasal to temporal ratio (N/T ratio) of the P1 amplitudes and the negative slope of the line between P1 and P2 (P1P2 Slope) in the nasal field were larger at each glaucoma stage except at the PPG stage. Both the N/T amplitude ratio and P1P2 Slope were weakly but significantly correlated with the MD (r = -0.3139, P<0.0001; r = 0.4501, P<0.0001, respectively), and the OCT parameters (all P<0.0001) except the outer layer thickness. Our findings indicate that the amplitudes of P1 and P2 of the second order kernel of the mfERGs in the nasal field of the center region can be good markers for the stages of glaucoma.

Comparison of Ocular Wavefront Aberration Measurements Obtained Using Two Hartmann-Shack Wavefront Aberrometers.

To assess agreement between measurements of ocular wavefront aberrations obtained using the Pentacam AXL Wave (Oculus Optikgeräte GmbH) (Aberrometer A) and KR-1W (Topcon Corp) (Aberrometer B), both of which are based on the Hartmann-Shack principle. In this prospective case-control study, ocular wavefront aberrations measurements were obtained using both aberrometers in patients with keratoconus (KC) and control participants. Ocular wavefront aberrations were measured through the natural pupil without dilation using both devices in a dark room. For both aberrometers, accommodation was inhibited by automatically adding fogging. The individual Zernike coefficients from the second to fourth order were compared between the two aberrometers for a 4-mm pupil diameter. Twenty-six KC and 29 control eyes were assessed. Statistically significant correlations ( P <0.05) were observed for all Zernike coefficients, except for Z 4-2 in the control group. Bland-Altman analysis indicated good agreement between aberrometers and no statistically significant differences in the control group. However, in the KC group, patterns of proportional error were observed in vertical coma Z 3-1 (r=0.338, P =0.008), trefoil Z 4-4 (r=0.701, P =0.003), secondary astigmatism Z 4-2 (r=0.348, P =0.025), and spherical aberrations Z 40 (r=0.407, P =0.012). The Zernike coefficient values measured by the two aberrometers were well correlated in the control and KC groups. However, in eyes with KC, Aberrometer B tended to present greater values in several Zernike coefficients than Aberrometer A, suggesting that wavefront measurements obtained using the two aberrometers are not interchangeable in patients with KC.

Clinical evaluation of AI-assisted screening for diabetic retinopathy in rural areas of midwest China.

BackgroundAlthough numerous studies have described the application of artificial intelligence (AI) in diabetic retinopathy (DR) screening among diabetic populations, studies among populations in rural areas are rare. The purpose of this study was to evaluate the application value of an AI-based diagnostic system for DR screening in rural areas of midwest China.MethodsIn this diagnostic accuracy study, diabetes mellitus (DM) patients in the National Basic Public Health Information Systems of Licheng County and Lucheng County of Changzhi city from July to December 2020 were selected as the target population. A total of 7824 eyes of 3933 DM patients were enrolled in this screening; the patients included 1395 males and 2401 females, with an average age of 19–87 years (63±8.735 years). All fundus photographs were collected by a professional ophthalmologist under natural pupil conditions in a darkroom using the Zhiyuan Huitu fundus image AI analysis software EyeWisdom. The AI-based diagnostic system and ophthalmologists were tasked with diagnosing the photos independently, and the consistency rate, sensitivity and specificity of the two methods in diagnosing DR were calculated and compared.ResultsThe prevalence rates of DR according to the ophthalmologist and AI diagnoses were 22.7% and 22.5%, respectively; the consistency rate was 81.6%. The sensitivity and specificity of the AI system relative to the ophthalmologists’ grades were 81.2% (95% confidence interval [CI]: 80.3% 82.1%) and 94.3% (95% CI: 93.7% 94.8%), respectively. There was no significant difference in diagnostic outcomes between the methods (χ2 = 0.329, P = 0.566, P>0.05), and the AI-based diagnostic system had high consistency with the ophthalmologists’ diagnostic results (κ = 0.752).ConclusionOur research demonstrated that DR patients in rural area hospitals can be screened feasibly. Compared with that of the ophthalmologists, however, the accuracy of the AI system must be improved. The results of this study might lend support to the large-scale application of AI in DR screening among different populations.

The Value of Eccentric Infrared Photorefraction in Evaluating Keratoconus.

Nonlinearity in the luminance profile of eccentric, infrared photorefraction may be used to differentiate corneal diseases such as keratoconus that distort the cornea, relative to regular refractive errors. This study aimed to determine the profile of eccentric, infrared photorefraction in keratoconus as a prototypical disease model for distorted corneas and identify a parameter in this profile for differentiating such disease conditions from healthy controls. Photorefraction reflex of 75 eyes with forme fruste to advanced keratoconic cases and that of 75 eyes of controls with regular refractive errors (spherical equivalent, +0.50 to -11.75 D; astigmatism, -0.50 to -4.50 D across 0 to 180° axes) were obtained over their natural pupils under unaided viewing using a custom-designed photorefractor placed at 1 m from the subject. The test was repeated in 10 controls with 4 and 6 D of trial-lens-induced myopia and myopic astigmatism at 0, 90, 45, and 135°. Linear regression was performed on the luminance profile across the pupil, and the departure of the data from linearity was estimated using the average residual error of the fit (Res avg ). Photorefraction profiles varied linearly across the pupil in controls, with slopes increasing with refractive error ( r = 0.87; P < .001) and Res avg remaining invariant of refractive error ( r = -0.29; P > .4). Corresponding profiles in keratoconus significantly departed from linearity, with Res avg progressively increasing with disease severity ( r = 0.66; P < .001). Res avg of 0.03 gray-scale units/pixel distinguished keratoconus from controls with sensitivity increasing from 66.7 to 100% for mild to advanced keratoconus and specificity remaining ≥97.1% across disease severity. Induced myopia and myopic astigmatism produced predictable changes in luminance profile slopes but with no change in Res avg values. Unlike regular myopia and astigmatism, the photorefraction reflex is significantly nonlinear in keratoconus because of the distorted cornea. Measures of nonlinearity in luminance profile may be incorporated in commercial photorefractors for differentiating such disease conditions from regular refractive errors.

Electrophysiological Assessment in Birdshot Chorioretinopathy: Flicker Electroretinograms Recorded With a Handheld Device.

PurposeThe flicker electroretinogram (ERG) is a sensitive indicator of retinal dysfunction in birdshot chorioretinopathy (BCR). We explored recordings from a handheld device in BCR, comparing these with conventional recordings in the same patients and with handheld ERGs from healthy individuals.MethodsNon-mydriatic flicker ERGs, using the handheld RETeval system (LKC Technologies), were recorded with skin electrodes at two centers. At one center (group 1), the stimuli (85 Td·s, 850 Td background) delivered retinal illuminance equivalent to international standards; at the other center (group 2), a different protocol was used (32 Td·s, no background). Patients also underwent international standard flicker ERG recordings with conventional electrodes following mydriasis. Portable ERGs from patients were also compared with those from healthy individuals.ResultsThirty-two patients with BCR (mean age ± SD, 56.4 ± 11.3 years) underwent recordings. Portable and standard ERG parameters correlated strongly (r > 0.75, P < 0.01) in both groups. Limits of agreement for peak times were tighter in group 1 (n = 21; −4.3 to +2.0 ms [right eyes], −3.9 to 1.5 ms [left eyes]) than in group 2 (n = 11; −3.4 to +6.9 ms [right eyes], −4.8 to +9.0 ms [left eyes]). Compared with healthy controls (n = 66 and n = 90 for groups 1 and 2, respectively), patients with BCR showed smaller mean amplitudes and longer peak times.ConclusionsPortable ERGs correlated strongly with conventional recordings, suggesting potential in rapid assessment of cone system function in office settings.Translational RelevanceFlicker ERGs, known to be useful in BCR, can be obtained rapidly with a portable device with skin electrodes and natural pupils.

Simultaneous measurements of foveal and peripheral aberrations with accommodation in myopic and emmetropic eyes.

The difference in peripheral retinal image quality between myopic and emmetropic eyes plays a major role in the design of the optical myopia interventions. Knowing this difference under accommodation can help to understand the limitations of the currently available optical solutions for myopia control. A newly developed dual-angle open-field sensor was used to assess the simultaneous foveal and peripheral ( nasal visual field) wavefront aberrations for five target vergences from -0.31 D to -4.0 D in six myopic and five emmetropic participants. With accommodation, the myopic eyes showed myopic shifts, and the emmetropic eyes showed no change in RPR. Furthermore, RPR calculated from simultaneous measurements showed lower intra-subject variability compared to the RPR calculated from peripheral measurements and target vergence. Other aberrations, as well as modulation transfer functions for natural pupils, were similar between the groups and the accommodation levels, foveally and peripherally. Results from viewing the same nearby target with and without spectacles by myopic participants suggest that the accommodative response is not the leading factor controlling the amplitude of accommodation microfluctuations.

Higher order aberrations and retinal image quality during short-term accommodation in children

Changes in higher order aberrations (HOA’s) and retinal image quality during accommodation have not previously been examined in children. This study measured ocular HOA’s in ninety non-myopic, school-aged children during short-term accommodation tasks at 0, 3, 6, and 9 D demands presented via a Badal optometer mounted to a Hartmann-Shack wavefront aberrometer (COAS-HD, Wavefront Sciences). Eighty-four participants who exhibited active accommodation were included in the analyses. An eighth order Zernike polynomial was fit across a 2.3 mm, 4 mm, and natural pupil diameter to evaluate changes in refractive power vectors (M, J180, and J45), accommodation errors (lags and leads), HOA root mean square (RMS) variables, individual Zernike coefficients, and the visual Strehl ratio based on the optical transfer function (VSOTF). All HOA RMS variables changed significantly with accommodation, with the greatest change observed for the 9 D demand. Of the individual Zernike coefficients, primary (C40) and secondary spherical aberration (C60) exhibited the greatest magnitude of change, becoming negative and positive with increasing accommodation, respectively. The VSOTF changed significantly with greater accommodation for both the 4 mm and natural pupil size, becoming significantly worse for the 9 D demand. HOA’s increase and retinal image quality decreases significantly during higher levels of accommodation in children, similar to adults. These findings provide a greater understanding of the optical properties of children’s eyes and insights into possible mechanisms for the association between accommodation, near work, and refractive error development.

PEMANFAATAN FOLKLOR SENTANI SEBAGAI MEDIA PEMBELAJARAN LINGKUNGAN HIDUP DI SD NEGERI INPRES KLEUBLOUW, KAMPUNG HARAPAN, KABUPATEN JAYAPURA

Flood often happens in Sentani, especially when heavy rains. Flood usually is related to people’s ignorance in preserving their environment, i.e. illegal logging, water and land pollution. Children as the future generation have to know how to respect and preserve nature. This inisiative is utilizing folklore as media to learn environmental preservation in SD Negeri INPRES Kleublouw using folktales, oral poems (ehabla) and traditional poverbs that are almost extinct. The objectives of the activities are (1) giving awareness about the importance of preserving natural environment, (2) motivating teachers and pupils about learning using local sources, (3) encouraging revitalization of Sentani cultural heritages. Both teachers and pupils of SDN INPRES Kleublouw were involved. From the activity, it is hoped that Sentani children and teachers have freedom in utilizing contextual sources not only as materials of teaching-learning and but also using them as media of relearning and disseminating Sentani folkore and all the socio-cultural values embedded in them.Keywords: folklore Sentani, environment, folktale, oral poems, traditional poverbs

Рhotopic Negative Response for Testing the Function of Inner Retina: Registration Requirements and Comparison in the Eyes with Natural Pupil Width and in Conditions of Drug Mydriasis

Purpose: To evaluate the possibility of registration of the photopic negative response (PhNR) without pupil dilatation in healthy individuals to determine the dysfunction of neurons of the inner retina.Methods: 12 healthy persons (23 eyes) aged 24 to 40 years were examined. Refraction anomalies did not exceed 0.5 diopters. A PhNR was evaluated in photopic ERGs recorded on a blue background with red flashes of four intensities (0.375, 0.75, 1.5, 3.0 cd·s/m2) using the RETIport/scan21 (Roland Consult). First, ERG was recorded with the natural pupil (3.5 ± 0.2 mm). Then, the recording was repeated after drug mydriasis (average pupil size 8.7 ± 0.1 mm).Results. In eyes with natural pupil width, in comparison with drug mydriasis, PhNR amplitudes in responses to weakest stimuli (0.375 cd·s/m2) were significantly reduced. The effect of pupil size on the PhNR amplitude from a baseline was virtually absent in responses to higher strength flashes. This phenomenon can be associated with an irregular distribution of light over the retina with small pupil size, the effect of which is maximal in responses to weak flashes. For the maximal brightness stimuli (3.0 cd·s/m2), differences were found between groups of non-dilated and dilated pupils in the amplitudes of the b-wave and PhNR from the b-peak, which may reflect a decrease in the number of stimulated photoreceptors during ganzfeld stimulation when the pupil is not dilated.Conclusion. The effect of pupil size on the parameters of the PhNR was most significant in the ERG with minimal flash strength and it decreases in responses to flashes of higher brightness. If it is necessary to record the ERG without drug mydriasis, especially in screening studies, it is recommended to limit the protocol to estimate the PhNR from a baseline in responses to maximal flashes, and use the relative parameter — the amplitude ratio of PhNR/b. Keywords: photopic negative response, electroretinography, pupil width

Macular Pigment Optical Density Fluctuation as a Function of Pupillary Mydriasis: Methodological Considerations for Dual-Wavelength Autofluorescence

ABSTRACT Purpose of the study Macular pigment (MP), comprising the dietary carotenoids lutein, zeaxanthin and meso-zeaxanthin, is believed to benefit eye health and vision. Numerous clinical and research devices and techniques are currently available to facilitate MP optical density (MPOD) measurement. One of those techniques, dual-wavelength fundus autofluorescence (AF) is being increasingly used for measurement of MP in the eye. There is substantial methodological variation across the published studies that have employed this technique, including in relation to the use of mydriasis, the possible influence of which does not appear to have been addressed in the literature. This prospective cross-sectional study was designed to investigate the effect of mydriasis on MP measurement quality and MPOD values obtained with dual-wavelength AF using the Heidelberg Spectralis HRA+OCT device. Materials and Methods Twenty-one healthy participants were recruited to the study. The mean age of participants was 44.8 years (± 14.63). Pupil size and MPOD were measured in one eye for each participant, initially under natural pupil conditions and subsequently 30 minutes following instillation of one drop of 0.5% tropicamide. Results Despite providing MPOD measurements for the majority of undilated eyes (85.7% of eyes herein), pupillary dilation resulted in statistically significant changes in MPOD (p < .001 for central eccentricities). Our results indicate that the changes in MPOD were not uniform across the spatial profile. Marked improvements were also observed in image quality post-dilation (p < .002 for central eccentricities). Conclusions This study clearly demonstrates that dual-wavelength AF measurements of MPOD in the same eye vary as a function of pupillary dilation status, with MPOD under-estimated across the entire spatial profile of MP for natural relative to dilated pupillary conditions. Mydriasis should, therefore, be used routinely for MPOD measurements using dual wavelength AF, pupil size should be reported and image quality optimized in order to ensure accurate MPOD quantification.

Effects of recording sequence on flicker electroretinographics recorded with natural pupils corrected for pupil area.

BackgroundA new handheld electroretinographic (ERG) recording system can record ERGs without mydriasis. However, this RETeval system cannot record ERGs from both eyes simultaneously. Thus, the purpose of this study was to determine whether the sequence of the ERG recordings will alter the results.MethodsWe studied 30 eyes of 30 healthy subjects. The flicker ERGs were recorded with the RETeval system without mydriasis and were elicited by 8, 16 and 32 photopic Td‐s. The flicker ERGs were recorded at two sessions. Session 1, the ERGs were recorded from the right eye and then the left eye, and Session 2, ERGs were recorded from the left eye then the right eye. We compared the implicit times, amplitudes and pupil diameters of the right eye between these two sessions.ResultsThe implicit time of the flicker ERGs was significantly shorter (p < 0.001), and the pupil diameters were significantly smaller (p = 0.013) at Session 2 than Session 1 but only for the lower stimulus intensity of eight Td‐s. There was a significant correlation of the differences in the implicit times and the differences in the pupil diameter between the two sessions (r = 0.406, p = 0.026).ConclusionsThe results indicate that the implicit times of the fundamental components of RETeval flicker ERGs can be affected by the sequence of recordings for lower stimulus intensities. This was most likely due to the differences of the pupil diameter during the recordings. We recommend that stronger stimuli be used to record the RETeval flicker ERGs to minimize the effects of the sequence of recordings.

The Effect of Retinal Illuminance on the Subjective Amplitude of Accommodation.

We show that the amplitude of accommodation decreases with retinal illumination even under photopic reading conditions and a constant pupil size. This result provides a basis for clinical approaches that are not based on an optical explanation. We investigated the effect of retinal illuminance on the amplitude of accommodation while the pupil of the eye remained constant. The amplitudes of accommodation of 10 young subjects (from 20 to 38 years of age) and that of 10 presbyopic subjects (from 45 to 54 years of age) were measured subjectively through an artificial pupil of 5 mm using a Badal optometer and for four values of retinal illuminance: 222, 821, 2138, and 5074 trolands. Phenylephrine was instilled to all the subjects to ensure that their natural pupil was greater than the artificial one in all experimental runs. Linear mixed-effects model for repeated measures with age and log luminance as covariates were used to check whether changes in amplitude of accommodation with retinal illumination were statistically significant. In the range of illuminances tested, the amplitude of accommodation decreased on average from 6.34 to 4.35 D in the young subjects and from 1.69 to 1.04 D in the presbyopic subjects. Illuminance was associated with the amplitude of accommodation in both young and presbyopic groups, with P < .01. The reduction in the amplitude of accommodation with target illumination (a phenomenon named night presbyopia) under photopic light conditions is not only due to a reduction in the depth of focus as a consequence of pupil dilation; it is strongly affected by the decrease of retinal illumination.

Pupil Size Estimation Based on Spatially Weighted Corneal Flux Density

The pupil size is an important parameter in different studies on vision and ophthalmology. A pupil size estimation model is constantly needed when actual measurements are unavailable. The reported pupil estimation models commonly adopt the product of light intensity and viewing field area, supposing the light contributes uniformly across the spatial domain. In this paper, the pupil diameters were measured for stimuli with different intensities and different sizes. Spatially varying effect were observed, especially for large field stimuli and annular bright stimuli. A spatially weighted flux density is proposed which shows a high correlation with pupil diameters. A hyperbolic equation is fitted to estimate the natural pupil diameter with independent light spatial distributions. The goodness of fit R 2 reaches 0.97. The accuracy of the model is further verified with a natural indoor scene for different viewing distances and different illumination levels. The model predicted pupil diameters show a high correlation with the measured data.

Effect of topical pilocarpine on refractive surgery outcomes.

To investigate the effect of topical pilocarpine on topical cycloplegia and on the results of refractive surgery. The study included 100 eyes of 100 patients who underwent laser-assisted in situ keratomileusis. Group 1 comprised patients who wanted to undergo surgery on the same day after cycloplegic examination and were applied with 2% pilocarpine hydrochloride; group 2 comprised patients whose pupils spontaneously went into the natural position. Corneal thickness, mean refractive spherical equivalent (MRSE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), pupil diameter, pupil center shift and high-order aberrations (HOAs) were compared between the two groups. There were no statistically significant differences between the groups in respect of preoperative age, gender, corneal thickness, MRSE, UDVA and CDVA. The pupil diameter was not statistically significant between the groups. Pupil diameter after pilocarpine was not statistically significant when compared with the natural pupil diameter. There were no statistically significant differences in postoperative HOA between the two groups. The pupillary dilatation and the associated pupillary shift were reduced with pilocarpine. Postoperative refractive values and aberrations showed no difference between the groups.

Monocular accommodation response to random defocus changes induced by a tuneable lens

Accommodation of the human eye relies on multiple factors and visual cues that include object size, monochromatic and chromatic aberrations, and vergence. Yet, even in monocular conditions, accommodation corrects for defocus. Studies of eye growth in chicks have addressed whether the retina can decode the sign of defocus as this may play a role for emmetropization and possibly also accommodation. However, findings have not been unambiguous and questions remain. Here, we report on monocular accommodation studies of emmetropic and myopic human subjects to clarify whether foveal vision drives accommodation in the correct direction by removing out-of-focus blur potentially before relying on other cues. Subjects viewed monocularly a green target at 1-meter distance while being presented with a random sequence of negative defocus step changes induced by a pupil-conjugated current-driven tuneable lens. The natural pupil was constricted by a pupil-conjugated motorized iris using three different diameters and target brightness was set with a liquid crystal variable attenuator. A Hartmann-Shack wavefront sensor with an infrared beacon captured real-time changes of defocus and Zernike polynomial coefficients up to 4th radial order. We find that the young adult eye accommodates reliably in the correct direction but with a latency of 300–700 ms. The findings are discussed in relation to an absorption model of light in outer segments that breaks the defocus symmetry and thus may serve as a plausible guide for accommodation and emmetropization.

A safe treatment for congenital fibrovascular pupillary membrane

The purpose of this study was to describe the clinical features and management of fibrovascular pupillary membrane. Four patients with congenital fibrovascular pupillary membrane were recruited. Comprehensively, ophthalmic examinations were performed. Peripheral iridectomy was performed to create a tunnel for blunt dissection of adhesion between the membrane and the lens capsule. Bipolar radiofrequency diathermy was then used to cut the membrane utilizing its coagulation effect. All four patients received uneventful membranectomy surgeries. The follow-up duration ranged from 9 to 16 months. All patients recovered well. Visual behavior was central and steady. The natural pupil size ranged from 2 to 3 mm. No sign of visual axis obstruction, cataract formation, or intraocular pressure elevation was detected during the follow-up. No second surgery was needed for all patients. Fibrovascular pupillary membrane is a rare unilateral disease impairing visual acuity in children. Using the technique combining peripheral iridectomy with bipolar radiofrequency, diathermy can simplify the traditional surgery procedures and reduce the risks when removing fibrovascular pupillary membranes.