Prediction of pupil size under binocular open-view settings using the new CASIA2 device.

PURPOSE: Pupillometry should be performed under conditions as close to natural viewing as possible. The present study aimed to determine whether pupil size in binocular open-view settings can be predicted based on pupil size measured using the CASIA2 device. METHODS: The present study included 61 participants (25 men and 36 women; mean age, 49 ± 15 years; age range, 22-69 years) with no history of ophthalmic disease other than refractive errors and cataract. We measured pupil size using the new CASIA2 device and a binocular open-view digital pupillometer (FP-10000II, TMI Co., Ltd., Saitama). Intra-class and inter-class reliabilities were evaluated by measuring pupil times three times with each device (two independent examiners) in 21 of the 61 participants. Reproducibility was analyzed using intra-class and inter-class correlation coefficients (ICCs). Regression formulae for calculating FP10000II pupil size based on CASIA2 pupil size were developed via simple linear regression analyses. RESULTS: Both devices exhibited high ICC values (> 0.80). The regression formulae for calculating the FP10000II pupil size for the distant and near views based on CASIA2 pupil size were y = 0.5702x + 0.4611 (determination coefficient, 0.67) and y = 0.502x + 0.445 (determination coefficient, 0.64), respectively. CONCLUSIONS: Pupil size under binocular open-view settings can be predicted based on simultaneous measurement of pupil size during evaluation of the anterior segment using the CASIA2 device. The calculated pupil size may represent a useful index for determining the most appropriate treatment strategy in candidates for cataract and refractive surgery.

Factors Influencing Visual Acuity in Fuchs' Endothelial Corneal Dystrophy.

SIGNIFICANCE: In eyes with mild Fuchs' endothelial corneal dystrophy without significant corneal edema, objective scattering index has the strongest influence on distance visual acuity, followed by the anterior corneal densitometry. Our findings suggest that distance visual acuity deteriorates in eyes with higher forward light scatter. PURPOSE: To evaluate the factors affecting distance visual acuity in patients with Fuchs' endothelial corneal dystrophy. METHODS: This retrospective study comprised 31 eyes of 31 patients with mild Fuchs' dystrophy without corneal edema and 25 eyes of 25 age-matched healthy subjects. Stepwise multiple regression analysis was used to assess the relationship between distance acuity with age, sex, forward light scatter, corneal backward scatter, anterior and posterior corneal higher-order aberrations, endothelial cell density, central corneal thickness, and corneal astigmatism. RESULTS: The forward light scatter, corneal backward scatter, and corneal higher-order aberrations were significantly larger in the Fuchs' dystrophy group than those in the control group (P ≤ .004). In a univariate analysis, with higher forward light scatter, anterior corneal backward scatter, corneal higher-order aberrations, and age, the distance acuity significantly deteriorated in eyes with Fuchs' dystrophy. In a multiple linear regression analysis, explanatory variables relevant to the distance acuity were the forward light scatter (P < .001, partial regression coefficient B = 0.035) and anterior corneal backward scatter (P = 0.2, B = 0.008) (adjusted R = 0.694). CONCLUSIONS: Eyes with higher light scatter, especially forward light scattering, showed deteriorated visual acuity. Results suggest that forward light scatter and corneal backward scatter play a more important role in visual performance than corneal higher-order aberrations in Fuchs' endothelial corneal dystrophy.

Etiology and outcomes of secondary surgical intervention for dissatisfied patients after pseudophakic monovision.

PURPOSE: To evaluate the etiology and the clinical outcomes of secondary surgical interventions for dissatisfied patients after pseudophakic monovision. SETTING: Department of Ophthalmology, Kitasato University Hospital, Kanagawa, Japan. DESIGN: Retrospective case series. METHODS: This study comprised 12 eyes in 12 patients (age 66.2 ± 5.6 years) who underwent photorefractive keratectomy (PRK) enhancement to improve their dissatisfaction after pseudophakic monovision. We quantitatively assessed the visual and refractive outcomes and the subjective satisfaction measured using a visual analog scale, that ranged from 0 (very dissatisfied) to 10 (very satisfied), before and 3 months after PRK enhancement. RESULTS: Six (50%) of the 12 patients were dissatisfied with their various distance visions because of a large amount of anisometropia (≥2.50 D). Two (16.7%) were dissatisfied with their distance vision after conventional monovision because of residual cylindrical errors (≥0.75 D) in the dominant eye. Three (25%) was an unknown origin. The remaining one of the 12 patients was dissatisfied due to the unadaptability to crossed monovision. Eleven (91.7%) eyes were within ±0.5 D of the targeted correction after PRK enhancement. The overall satisfaction score was significantly improved, from 3.7 ± 2.4 (range 0-7) preoperatively to 6.0 ± 2.4 (range 2-9) postoperatively (p = 0.02). No vision-threatening complications were seen throughout the observation period. CONCLUSIONS: PRK enhancement was effective with predictable refractive results and thus improved patient satisfaction for dissatisfied patients after pseudophakic monovision. These findings also suggest that the accurate correction of refractive errors plays a key role in successful pseudophakic monovision.

Effect of Scattering and Aberrations on Visual Acuity for Band Keratopathy.

SIGNIFICANCE: The progressive accumulation of the calcification may deteriorate corneal transparency, especially in the interpalpebral area, and subsequent visual performance for patients with band keratopathy. However, the detailed quantitative analysis of light scattering or higher-order aberrations on visual performance for these patients so far has not been elucidated. PURPOSE: The aim of this study was to assess the relationship of intraocular forward scattering, corneal backward scattering, and corneal higher-order aberrations with visual acuity in eyes with band keratopathy. METHODS: This prospective study comprised 27 eyes of 27 consecutive patients who were diagnosed as having band keratopathy and age-matched 27 eyes of 27 healthy subjects. We quantitatively assessed objective scattering index using the double-pass instrument (Optical Quality Analysis System II; Visiometrics, Terrassa, Spain), corneal densitometry using the Scheimpflug rotating camera (Pentacam HR; Oculus, Wetzlar, Germany), and corneal higher-order aberrations using the Hartmann-Shack aberrometry (KR-9000; Topcon, Tokyo, Japan). RESULTS: The mean objective scattering index, corneal densitometry, corneal higher-order aberrations, and logarithm of the minimal angle of resolution (logMAR) visual acuity in eyes with band keratopathy were 5.14 ± 3.11, 36.42 ± 10.55 gray-scale units, 0.33 ± 0.10 µm, and 0.03 ± 0.11 logMAR, respectively. These parameters were significantly larger in the band keratopathy group than in those in the control group (Mann-Whitney U test, P < .001). We found significant correlations of visual acuity with the objective scattering index (Spearman correlation coefficient, r = 0.465, P = .015), but no significant association with the corneal densitometry (r = 0.082, P = .683) or with corneal higher-order aberrations (r = -0.073, P = .718), in eyes having band keratopathy. CONCLUSIONS: Intraocular forward scattering, corneal backward scattering, and corneal higher-order aberrations in eyes with band keratopathy were significantly higher than those in normal eyes. Visual acuity was significantly correlated with intraocular forward scattering, but not with corneal backward scattering or corneal aberrations in the band keratopathy group, suggesting that intraocular forward scattering plays a vital role in visual performance in eyes with band keratopathy.

Effect of hole size on fluid dynamics of a posterior-chamber phakic intraocular lens with a central perforation by using computational fluid dynamics.

BACKGROUND: A modified implantable collamer lens (ICL) with a central hole with a diameter of 0.36 mm, referred to as a hole-ICL, was created to improve aqueous humour circulation. The aim of this study is to investigate the ideal hole size in a hole-ICL from the standpoint of the fluid dynamic characteristics of the aqueous humour using computational fluid dynamics. METHODS: Fluid dynamics simulation using an ICL was performed with thermal-hydraulic analysis software FloEFD V 12.2 (Mentor Graphics Corp.). In the simulation, three-dimensional eye models based on a modified Liou-Brennan model eye with a conventional ICL (Model ICM, Staar Surgical) and a hole-ICL were used. The hole-ICL was -9.0 dioptres (D) and 12.0 mm in length, with an optic zone of 5.5 mm. The vaulting was 0.50 mm. The quantity of aqueous humour produced by the ciliary body was set at 2.80 µL/min. Flow distribution between the anterior surface of the crystalline lens and the posterior surface of the ICL was calculated, and trajectory analysis was performed. RESULTS: With an increase in the central hole size, the velocity of the aqueous humour increased, with the peak velocity occurring at a diameter of approximately 0.4 mm. Once the diameter had increased above 0.4 mm, the velocity then decreased. The velocity difference between the cases of a central hole size of 0.1 mm and 0.2 mm was significant. CONCLUSION: The desirable central hole size was 0.2 mm or larger in terms of flow dynamics. The current model, based on a central hole size of 0.36 mm, was close to ideal. The optimisation of the hole size should be performed based on results from a long-term clinical study so as to analyse the incidence rate of secondary cataract and optical performance.

[Epidemiological Study of Poor Visual Acuity among Schoolchildren in Bonin Islands].

PURPOSE: To investigate the change in uncorrected visual acuity (UCVA) among schoolchildren in Bonin Islands. SUBJECTS AND METHODS: UCVA of schoolchildren aged 6 to 14 years, was collected from reports of School Health Examination Surveys conducted from 1981 to 2012. The proportion of schoolchildren with poor UCVA in the Bonin Islands was compared with those in metropolitan Tokyo. The results in Bonin Islands were also divided into two groups, before- and after-1996 when terrestrial television broadcasting service has been started, and the data of those two groups were compared. RESULTS: The proportion of schoolchildren with poor UCVA in Bonin Islands was lower than that in Tokyo. Among the residents of Bonin Islands, the proportion of schoolchildren with UCVA of < 1.0 was higher in the after-1996 group than in the before- 1996 group, with a clear increase in schoolchildren with poor UCVA after 1996 (p < 0.01, Fisher's exact test), examined among the 4th grade of elementary school or above. After 1996, 26.6% of first graders at a public junior high school had poor UCVA of < 0.7, whereas before 1996 no such case could be detected. CONCLUSION: The present study revealed that the proportions of schoolchildren with poor UCVA in Bonin Islands was lower than that in Tokyo; but in the residents of Bonin Islands after 1996, the proportion of the schoolchildren with poor UCVA increased.

Two Cases of Severe Infectious Keratitis Treated with Corneal Collagen Crosslinking.

Purpose: Corneal collagen crosslinking (CXL) is effective not only in halting the progression of keratoconus but also in management of infectious keratitis. However, as far as we can ascertain, there are no reports of CXL for the treatment of severe infectious keratitis in Japan. Thus, we report 2 cases in which CXL was effective for infectious corneal ulcer. Cases: A 82-year old man and 76-year-old woman. Both of which were treated with local antibiotic therapy; however, the therapy was not empirically effective. Thus, we performed CXL following the standard Dresden protocol after obtaining informed consent from each case. Two weeks after CXL, slit-lamp examinations revealed improvements of corneal transparency and keratitis in each case. No serious complications such as corneal perforations and infectious recurrences occurred after the treatments. Conclusion: Two cases of infectious keratitis improved in corneal opacity and had showed inhibitory effect on infected cornea. CXL seems to be an effective therapeutic alternative in resistant cases of infectious keratitis, although the exact etiology of this effective treatment remains unclear.

Evaluation of Relative Afferent Pupillary Defect Using RAPDx Device in Patients with Optic Nerve Disease.

We previously reported the standard values of the amplitude and latency scores in the RAPDx device for evaluating relative afferent pupillary defect (RAPD). Here, we evaluated RAPD in patients with optic nerve disease by using these standard values. Twenty-eight patients with current or previous optic nerve disease were enrolled in this study. Additionally, the data of 84 healthy subjects from our previous report were used as control data. We measured the amplitude and latency scores using RAPDx. We then compared their mean values and the percentages of individuals with standard values within a certain range between the optic nerve disease group and healthy group. Additionally, we evaluated their correlation with visual acuity and the critical flicker fusion frequency in the optic nerve disease group. Both parameters were significantly higher in the optic nerve disease group than in the control group (p < 0.0001). The detection rate of RAPD when using the standard value of amplitude score was 75%. Additionally, both parameters showed a significant correlation with laterality-based differences in visual acuity and critical flicker fusion frequency values in the optic nerve disease group (r = 0.59-0.75, p < 0.001). The amplitude and latency scores determined using RAPDx are useful in evaluating RAPD, particularly the standard value of the amplitude score.

Influence of femtosecond lenticule extraction and small incision lenticule extraction on corneal nerve density and ocular surface: a 1-year prospective, confocal, microscopic study.

PURPOSE: To compare the influence of femtosecond lenticule extraction (FLEx) and small incision lenticule extraction (SMILE) on corneal nerve density and the ocular surface for equivalent degrees of correction of myopia. METHODS: Sixty eyes of 30 patients (8 males and 22 females, mean age: 31.0 ± 6.0 years) were included in the study. The patients underwent FLEx in 1 eye and SMILE in the other eye by random assignment. Subbasal nerve density was measured using confocal microscopy preoperatively and at 1 week, 1 and 3 months, and 1 year postoperatively. Ocular surface parameters such as Schirmer's test results, tear film break-up time, and corneal sensation were performed preoperatively and at 1 and 3 months postoperatively. RESULTS: In the FLEx group, subbasal nerve density was 18,390 ± 6,090 µm/mm(2) preoperatively and 5,770 ± 3,490 µm/mm(2) at 1 year postoperatively (P < .001, Dunnett's test). In the SMILE group, subbasal nerve density was 16,810 ± 6,220 µm/mm(2) preoperatively and 11,870 ± 8,200 µm/mm(2) at 1 year postoperatively (P = .21). The decrease in corneal nerve density was significantly less after SMILE than after FLEx at all postoperative visits (Mann-Whitney U test, P < .05). FLEx resulted in a significant decrease in Schirmer's test results, tear film break-up time, and corneal sensation at all postoperative visits, whereas SMILE induced no significant changes in these parameters (P > .05). CONCLUSIONS: There was less damage to the sub-basal nerve plexus of the cornea and less effect on the ocular surface parameters after SMILE than after FLEx.

Intraocular Scattering after Instillation of Diquafosol Ophthalmic Solution.

PURPOSE: To assess the changes in intraocular scattering before and after instillation of diquafosol ophthalmic solution in patients with short tear breakup time (TBUT) dry eye. METHODS: We prospectively examined 20 eyes of 20 short TBUT dry eye patients (study group) and age-matched 20 eyes of 20 healthy subjects (control group). Intraocular scattering was measured as the objective scattering index (OSI) at 0.5-second intervals over 10 seconds without blinking. Patients were instructed to start topical administration of 3% diquafosol ophthalmic solution six times daily for 4 weeks. RESULTS: The OSI significantly deteriorated after 7.0 seconds compared with the initial value of OSI after the blinking in the study group. The OSI was also significantly higher in the study group than in the control group at 4.5 to 10.0 seconds after the blinking (p < 0.05). We found significant improvements 2 weeks after treatment not only in TBUT (p < 0.001) but also in the mean OSI, the OSI change rate, and the slope of the linear regression line of the OSI within 10 seconds (p < 0.001, p = 0.003, and p = 0.002, respectively). We also found significant improvements 4 weeks after treatment in these variables. CONCLUSIONS: Intraocular scattering deteriorates significantly with time in patients with short TBUT dry eye. Diquafosol ophthalmic solution exhibits an improvement not only in TBUT but also in intraocular scattering, indicating that diquafosol is also effective for improving the optical quality of the eye.

Pupillary Size and Light Reflex in Premature Infants.

The authors examined pupillary light reflexes to both red and blue stimuli using infrared video-pupillography in premature infants. Pupillary light reflexes were obtained in response to 470 nm blue and 635 nm red stimuli with varying intensities of 10 cd/m2 and 100 cd/m2. Red stimuli did not evoke a pupillary response in premature infants. However, blue stimuli produced a pupillary reflex, and the extent of the reaction was dependent on the intensity of the stimulus. These results suggest that in premature infants, the origin of light reflex may be mediated predominately by melanopsin-containing retinal ganglion cells.

Enhanced Depth Imaging of Central Laminar Thickness in Optic Neuropathy: Comparison with Normal Eyes.

The purpose of this study was to compare central laminar thickness (LT) among patients with glaucomatous optic neuropathy (GON), patients with non-GON, and normal subjects using enhanced-depth imaging optical coherence tomography (EDI-OCT). Enrolled were 57 patients (n = 64 eyes), including 30 women and 27 men. Three groups were identified: GON (n = 18 eyes), non-GON (n = 16 eyes), and control (n = 30 eyes). The GON group comprised eyes with primary open-angle glaucoma (POAG) (n = 9) and normal-tension glaucoma (NTG) (n = 9). The non-GON group comprised eyes with demyelinating optic neuritis (n = 9), anterior ischemic optic neuropathy (AION) (n = 2), compressive ON (n = 2), Leber hereditary ON (n = 2), and traumatic ON (n = 1). GON and non-GON groups were further divided into mild, moderate, and severe subgroups. Inclusion in the GON group was based on mean deviations (MDs) of visual fields; inclusion in the non-GON group was based on critical flicker frequency (CFF) responses. Intraclass correlation coefficients (ICCs) were used to verify reproducibility of measurements. LTs of GON and non-GON group eyes were thinner than those of control group eyes (p < 0.01); LTs of GON group eyes were thinner than those of non-GON group eyes (p = 0.01). LTs of severe GON subgroup eyes were thinner than those of moderate and mild GON subgroup eyes (p < 0.001; p = 0.024, respectively). LTs of severe non-GON subgroup eyes were thinner than those of mild non-GON subgroup eyes (p = 0.002). These results show that EDI-OCT is valuable for documenting structural abnormalities in optic neuropathy (ON).

Comparison of astigmatic correction after femtosecond lenticule extraction and wavefront-guided LASIK for myopic astigmatism.

PURPOSE: To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx) and wavefront-guided LASIK in eyes with myopic astigmatism. METHODS: Fifty-eight eyes of 41 patients undergoing FLEx and 49 eyes of 29 patients undergoing wavefront-guided LASIK to correct myopic astigmatism were examined. Visual acuity, cylindrical refraction, predictability of the astigmatic correction, and astigmatic vector components were compared between groups 6 months after surgery. RESULTS: There was no statistically significant difference in manifest cylindrical refraction (P = .08) or percentage of eyes within ± 0.50 diopter (D) of its refraction (P = .11) between the surgical procedures. The index of success in FLEx was statistically significantly better than that of wavefront-guided LASIK (P = .02), although there was no significant difference between the groups in other indices (eg, surgically induced astigmatism, target-induced astigmatism, astigmatic correction index, angle of error, difference vector, and flattening index). Subgroup analysis showed that FLEx had a better index of success (P = .02) and difference vector (P = .04) than wavefront-guided LASIK in the low cylinder subgroup; the angle of error in FLEx was significantly smaller than that of wavefront-guided LASIK in the moderate cylinder subgroup (P = .03). CONCLUSIONS: Both FLEx and wavefront-guided LASIK worked well for the correction of myopic astigmatism by the 6-month follow-up visit. Although FLEx had a better index of success than wavefront-guided LASIK when using vector analysis, it appears equivalent to wavefront-guided LASIK in terms of visual acuity and the correction of astigmatism.

Secondary IOL implantation for an aphakic patient with congenital cataract living in Bonin Islands; follow-up study.

Introduction: We previously reported a case of a patient with bilateral congenital cataract identified in the Ogasawara village, Bonin Islands, Japan, on a visit by an ophthalmologist and describe its course over 17 years from initial surgery. Here, we report on a secondary intraocular lens (IOL) implantation that was subsequently performed at 22 years and 5 months of age. Methods: After cataract surgery at 7 months, the aphakic patient began amblyopia treatment using extended-wear soft contact lenses (SCLs). After 10 years of age, SCLs were chosen to achieve crossed monovision considering the cosmetic appearance when facing other people. At 22 years of age, a secondary IOL implantation was performed. Secondary implant in the patient considered appearance and postoperative vision without glasses, we selected the crossed monovision method using a monofocal IOL. The postoperative targeted refraction for the right (non-dominant eye) and left eyes (dominant eye) planed - 0.33D and - 2.25D, respectively. Results: At 3 months after surgery, the corrected distance visual acuity (CDVA) with IOLs for the right and left eyes was 20/16 and 20/60, respectively, and the binocular visual acuity was 20/16 for distant vision and 20/25 for near vision. The CDVA for the right eye was: 20/13 × IOL = sph-0.25D and that for the left eye was: 20/13 × IOL = sph -1.75D D/cyl -0.50D/Ax170°. Although the exotropia was complicated by dissociated horizontal deviation and dissociated vertical deviation, there were no significant changes in ocular position before and after surgery. The patient was satisfied with achieving independence from spectacles and SCLs. Conclusion: The use of the crossed monovision method with monofocal IOLs in this patient and defective binocular function created a visual environment with no inconvenience in everyday life after secondary IOL implantation. In terms of secondary implant after amblyopia treatment, the IOL type or postoperative targeted refraction must be chosen to maintain or improve the visual environment obtained with the amblyopia treatment.

Association between ocular dominance and refractive asymmetry.

PURPOSE: To investigate the association between ocular dominance (sighting dominance) and refractive asymmetry in phakic patients. METHODS: This retrospective study included 3,012 patients with a mean age of 29.0 ± 5.3 years (range: 20 to 39 years). Refractive error was determined with cycloplegic refraction and axial length was determined with IOLMaster (Carl Zeiss Meditec, Dublin, CA). Ocular dominance was assessed using the hole-in-the-card test. RESULTS: The right and left eyes were dominant in 77.7% and 22.3% of the patients, respectively. In the high anisometropia group (⩾ 2.0 diopters), the non-dominant eyes had significantly higher myopic spherical equivalents and longer axial lengths than the dominant eyes (P < .05). However, there were no significant differences in these parameters in the low anisometropia group. CONCLUSION: The current study revealed that non-dominant eyes had a greater myopic refractive error and longer axial length than the dominant eyes, especially in the patients who had high amounts of anisometropia.

A modified glaucoma staging system based on visual field index.

PURPOSE: To describe a modified glaucoma staging system (Modified GSS) based on the visual field index (VFI) and evaluate the performance of the Modified GSS compared with the Bascom Palmer GSS and Enhanced GSS. METHODS: A total of 549 eyes of 549 patients were studied retrospectively. The Modified GSS was used to classify the glaucomatous visual field defects into stage 0 to 5 based on the VFI. The cutoff values for each stage were derived from VFI that were equivalent to mean deviations of -6, -12, -20, and -25 dB by receiver operating characteristic analysis. The staging performances, based on each of three GSSs, were compared with both the Advanced Glaucoma Intervention Study (AGIS) and Collaborative Initial Glaucoma Treatment Study (CIGTS) scores. RESULTS: The VFI cutoff values calculated for each stage were 81.5, 62.5, 42.5, and 22.5%, respectively. The correlation coefficient of Modified GSS was greater than that of Bascom Palmer GSS (p < 0.001), and correlation coefficients of Modified GSS and Enhanced GSS were equivalent. However, Enhanced GSS tended to classify moderate to severe AGIS and CIGTS scores into higher stages (p < 0.001). CONCLUSIONS: The Modified GSS is easy to use and accurate, and the staging performance is either equal or superior to existing GSSs.

The impact of real-time 3d imaging by ultra-high speed optical coherence tomography in urothelial carcinoma.

BACKGROUND: Optical coherence tomography (OCT) has become a promising diagnostic tool in many medical fields. In particular, noninvasive real-time optical biopsy of internal organs is one of the most attractive applications of OCT, enabling in situ diagnosis of carcinoma at an early stage. We used an ultra-high speed OCT system for real-time three-dimensional (3D) imaging of three excised specimens of advanced urothelial carcinoma (UC) and investigated the association of the images with results from histopathological examination. CASE PRESENTATIONS: Case 1 was a 69-year-old man underwent radical cystectomy for muscle-invasive UC (pT2). Case 2 was a 53-year-old man underwent laparoscopic nephroureterectomy and partial cystectomy for left ureter carcinoma (pT2) and case 3 was a 77-year-old woman underwent radical cystectomy for advanced bladder carcinoma (pT3b). Real-time 3D OCT images of normal bladder wall and ureter showed three layers, including the urothelium, lamina propria, and muscularis layer. In contrast, normal structure was not seen in the muscle-invasive UC area or the scar tissue area. CONCLUSIONS: This study highlighted a new diagnostic method with potential application for UC diagnosis. We will investigate more cases in the future and expect improvement in the diagnosing efficiency of carcinoma in situ or organ-confined muscle-invasive cancer by cystoscopy or ureteroscopy with ultra-high speed OCT.

Clinical evaluation of accuracy of horizontal meridian limbal marking.

PURPOSE: To assess the horizontal meridian misalignment of limbal marking under a slit lamp microscope by means of anterior segmental image assessment. METHODS: A consecutive series of the 32 eyes of 16 subjects (7 males and 9 females) aged 29 ± 6 years (range, 23-44 years), who had refractive errors but were otherwise healthy, were used in this study. With each subject seated at the slit lamp and a coaxial slit turned to the horizontal meridian, we aligned the subject's head vertically and placed two reference marks aligned with the 3- and 9-o'clock positions on the limbal conjunctiva, using a marker pen or a toric marker. We quantitatively evaluated the accuracy of axis aliment by determining deviation from the horizontal reference line using a corneal topographer with an anterior segment image. RESULTS: The amount of the axis misalignment was 3.4° ± 2.2° (range, 0°-8°) when the marker pen was used, and 6.9° ± 5.0° (range, 0-24°) when the toric marker was used. Location identification using the toric marker showed a significantly larger deviation in axis alignment than that using the marker pen (Wilcoxon sign rank test, p < 0.001). CONCLUSIONS: Horizontal limbal marking using a slit lamp microscope showed the axis misalignment by an average of 3.4° to 6.9°. These alignment errors led to a reduction of the effectiveness of astigmatism correction by an average of 10% to 20%, which was not necessarily negligible when we aim to correct astigmatism completely, if possible. For successful astigmatic surgical procedures, increased accuracy of preoperative limbal marking by decreased misalignment of the astigmatism axis is essential.

Fluid dynamics simulation of aqueous humour in a posterior-chamber phakic intraocular lens with a central perforation.

BACKGROUND: A modified implantable collamer lens (ICL) with a central hole (diameter, 0.36 mm), a "Hole-ICL", was created to improve aqueous humour circulation. The aim of this study was to investigate the fluid dynamic characteristics of aqueous humour in a Hole-ICL using computational fluid dynamics. METHODS: Fluid dynamics simulation using an ICL was performed with thermal-hydraulic analysis software FloEFD V5 (Mentor Graphics Corp.). For the simulation, three-dimensional eye models based on a modified Liou-Brennan model eye with conventional ICL (Model ICM, STAAR SURGICAL) and a Hole-ICL were used. Both ICLs were -9.0 diopters (D) and 12.0 mm in length, with an optic of 5.5 mm. The vaulting was 0.50 mm. The quantity of aqueous humour produced by the ciliary body was set at 2.80 µl/min. Flow distribution between the anterior surface of the crystalline lens and the posterior surface of the ICL was also calculated, and trajectory analysis was performed. RESULTS: The flow velocity 0.25 mm in front of the centre of the crystalline lens was 1.52 × 10(-1) mm/sec for the Hole-ICL and 1.21 × 10(-5) mm/sec for the conventional ICL. Outward flow from the hole in the Hole-ICL was confirmed by trajectory analysis. CONCLUSION: These results suggest that Hole-ICLs improve the circulation of aqueous humour to the anterior surface of the crystalline lens.

Effect of astigmatism on apparent accommodation in pseudophakic eyes.

PURPOSE: To investigate the factors affecting apparent accommodation in pseudophakic eyes from a clinical viewpoint and the effects of corneal and refractive astigmatism on this accommodation from an optical viewpoint. METHODS: We retrospectively examined 62 eyes of 33 patients who had undergone phacoemulsification with monofocal intraocular lens implantation. We quantitatively assessed the amplitude of apparent accommodation using an accommodometer 3 months after surgery. Multiple regression analysis was used to assess the factors affecting apparent accommodation. We also estimated the accommodation in eyes with corneal astigmatism by optical simulation. RESULTS: The mean amplitude of apparent accommodation was 1.58 = 0.65 D. Explanatory variables relevant to this accommodation were in order of influence, pupil diameter (partial regression coefficient B = 0.293, p = 0.008), and corneal multifocality (B = 0.101, p = 0.03). Other explanatory variables such as age, gender, axial length, corneal astigmatism, and refractive astigmatism showed no significant relationship with this accommodation. The estimated apparent accommodations for a 3.0 mm pupil by optical simulation were 1.25, 1.25, 1.25, 0.75, and 0 D, in eyes with corneal astigmatism of 0, 0.5, 1.0, 1.5, and 2.0 D, respectively. Similar results were obtained for a 4.0 mm pupil. CONCLUSIONS: Eyes with smaller pupil diameter and eyes with greater corneal multifocality are more predisposed to have greater apparent accommodation. However, from clinical and optical viewpoints, corneal or refractive astigmatism does not significantly contribute to apparent accommodation after cataract surgery, suggesting that it may be of less significance that the astigmatism is consciously retained in consideration of this accommodation in astigmatic eyes.