Corneal Diameter Measurements Research Articles

Normative ocular data for juvenile and adult Japanese quail (Coturnix japonica).

To obtain normative ocular data for Japanese quail as they mature from juveniles to adults. Twenty-six captive Japanese quail comprising thirteen males and thirteen females, free of ocular disease, were included in the study. Ophthalmic reference values were measured in both eyes at 1 and 5months of age. A complete ophthalmic examination was performed, including neuro-ophthalmic reflexes, slit lamp biomicroscopy, phenol red thread test (PRTT), rebound tonometry, fluorescein staining, horizontal corneal diameter measurement, indirect ophthalmoscopy, and ocular ultrasound biometry. Ultrasound biomicroscopy measurements of axial globe length, lens thickness, vitreal chamber length, and pecten length were recorded. The depth of the anterior chamber was calculated by subtracting the lens thickness and vitreous length from the axial globe length. Measures of association and descriptive statistics were analyzed using STATA-14 and STATA-15. Juvenile and adult females were heavier than age-matched males. Weight, intraocular pressure, horizontal corneal diameter, axial globe length, and lens thickness measurements increased with age. No statistically significant differences were found in the remainder of measurements among individuals in different sex or age-groups. This work provides reference values and clinical findings that can be used in future research on quail and ocular disease.

Ophthalmic findings in cinereous vultures (Aegypius monachus).

The aim of the present study was to provide ophthalmic reference values under normal physiological conditions for Aegypius monachus (cinereous vulture). Thirty-two eyes of sixteen adult captive cinereous vultures were used for this study. Tear tests and tonometry in conscious and anesthetized states, neuro-ophthalmic tests, measurement of corneal diameter, slit-lamp biomicroscopy, ophthalmoscopy, and funduscopy were performed. Schirmer tear test (STT) value was 11.4±2.6 and 11.5±2.8mm/min in the right (OD) and left eye (OS), respectively. Phenol red thread test (PRT) values were 22.3±2.1mm/15s OD and 22.8±3.0mm/15s OS. The results showed a strong correlation between STT and PRT in both eyes. Intraocular pressure (IOP) values were 32.8±6.9mmHg OD and 31.9±7.1mmHg OS with TonoVet and 20.7±4.5mmHg OD and 19.5±4.1mmHg OS with Tono-Pen. There were significant differences in IOPs between rebound and applanation tonometry in both OD and OS. Tear production and IOP values showed significant reductions with general anesthesia in both tear tests and both tonometry (P<.001). Horizontal corneal diameter (mm) was 15.56±0.96 OD and 15.56±0.96 OS. Vertical diameter (mm) was 14.13±0.96 OD and 14.06±1.06 OS. The horizontal diameter was significantly longer than vertical diameter (P<.001). Ocular morphologic information and normal reference range values for various ophthalmic measurements were obtained in clinically healthy cinereous vultures, which can facilitate accurate diagnosis and better management of ophthalmic diseases in cinereous vultures.

Comparative analysis of 2 swept-source optical coherence tomography biometers

To report the level of agreement, repeatability, and correlation of axial length (AL), mean keratometry, central corneal thickness, anterior chamber depth, lens thickness, and corneal diameter measurements of 2 swept-source optical coherence tomography (SS-OCT) biometers, the IOLMaster 700 (reference biometer) and the Argos (new biometer). Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Retrospective case series. Each patient had SS-OCT biometry with the reference biometer and new biometer. In addition to reporting the statistical results derived from both eyes, this study included a subgroup analysis of right eyes and left eyes. The level of agreement between the biometers was represented with the Bland-Altman method. Power vector analysis of the J0 (Jackson cross-cylinder, axes at 0 degrees and 90 degrees) and J45 (Jackson cross-cylinder, axes at 45 degrees and 135 degrees) vectorial components of astigmatism was performed. Internal consistency was assessed with the Cronbach α coefficient of reliability. The dispersion of probability distribution was computed with the coefficient of variation. The intraoperator repeatability was calculated using the intraclass correlation coefficient (ICC). The study comprised 112 patients (218 eyes). There was a statistically significant difference between the 2 biometers in all measurements (P<.05) except AL. The level of correlation between the reference biometer and the new biometer was very high for all the parameters except corneal diameter, and the agreement was high. The ICC and internal consistency were excellent with both biometers. The new biometer provided good agreement and repeatability compared with the reference biometer.

OPHTHALMIC EXAMINATION IN COMMON KESTRELS (FALCO TINNUCULUS) FROM SOUTH KOREA.

The purpose of this study was to establish reference ophthalmic findings in the common kestrel (Falco tinnunculus). Twenty healthy adult kestrels were included in this study. Ophthalmic examinations included slit lamp biomicroscopy, fundus exam, Schirmer tear test, conjunctival bacterial culture and isolation, corneal touch threshold, tonometry, and corneal diameter measurement. Mean tear production was 7.4 ± 3.27 mm/min, and mean intraocular pressure measured via applanation tonometry was 10.5 ± 3.15 mm Hg. In addition, the mean corneal touch threshold was 29.8 ± 20.1 mm, and the mean corneal diameter was 9.8 ± 1.1 mm. Of the 25 conjunctival swabs, 23 (92%) yielded bacterial growth. Most of these bacteria were gram positive (69.6%); the most predominant genus was Staphylococcus. This study presents reference values for ophthalmic examinations in common kestrels.

Agreement of Corneal Diameter Measurements Obtained by a Swept-source Biometer and a Scheimpflug-based Topographer.

To assess the agreement between a swept-source optical biometry device (IOLMaster 700) and a Scheimpflug-based topography device (Pentacam HR) in measuring the corneal diameter. A total of 100 eyes from 100 cataract surgery candidates were enrolled. The white-to-white (WTW) distance measurements provided by both devices were recorded and analyzed. A paired t test was performed to compare the mean values of the WTW distance between the IOLMaster 700 and Pentacam HR. The Bland-Altman analysis was used to evaluate the agreement between the measurements of both devices. Mean age (±SD) of the participants was 65.9 ± 3.3 years, and 58 (58%) were men. The mean WTW distances measured by the IOLMaster 700 and Pentacam HR were 11.72 ± 0.45 mm and 11.41 ± 0.42 mm, respectively (P < 0.001). The overall 95% limits of agreement were -0.17 and 0.78 mm. The 95% limits of agreement between the measurements of the 2 devices were -0.30 and 0.84 versus -0.07 and 0.72 for eyes with WTW distances of ≤11.50 mm versus >11.50 mm, respectively. According to the results of this study, the IOLMaster 700 may overestimate the WTW distance measurements by up to 0.78 mm compared with the Pentacam HR, so these 2 devices should not be used interchangeably for this purpose. The agreement is somehow weaker for eyes with WTW distances of 11.50 mm or less than those with WTW distances greater than 11.50 mm.

Objective Evaluation of Corneal and Lens Clarity in Children With Type 1 Diabetes Mellitus

To investigate whether abnormal glucose metabolism and duration of diabetes mellitus (DM) affected the corneal and lens clarity in children with well-controlled type 1 DM and to compare the results obtained with those in healthy children. Cross-sectional prospective study. This multicenter study enrolled 56 patients with DM and 51 control subjects. The duration of DM and the glycosylated hemoglobin (HbA1c) levels of the patients in the DM group were recorded. The Pentacam HR imaging system was used for corneal densitometry (12-mm corneal diameter) measurements. Furthermore, the lens densitometry and lens thickness (LT) measurements were performed after dilation of the pupils, using the same Pentacam HR device. The corneal densitometry values were similar in all concentric zones and layers in both groups (P > .05, for all). The mean values of the average and maximum lens densitometry measurements of the 2 groups, as well as the mean LT values, were statistically significantly different (P= .021, P= .011, and P < .001, respectively). There were statistically significant correlations between the lens densitometry values and the duration of DM (P < .05, for all). Conversely, no statistically significant relationship was found between the lens densitometry values and HbA1c levels (r= 0.743; P= .084). The children with type 1 DM had decreased lens clarity and increased LT, even in cases of well-controlled DM, without DR. It is reasonable to think that these changes might have been caused by the type 1 DM.

Safety and efficacy of collagen matrix implantation in infantile glaucoma.

To evaluate the preliminary results of biodegradable collagen matrix implant (Ologen) designed to improve outcome in patients with infantile glaucoma undergoing combined trabeculotomy and trabeculectomy. A biodegradable collagen matrix (OculusGen) was placed in the subconjunctival space, partially over the scleral flap and the sclera in 20 eyes of 11 patients with infantile glaucoma who underwent combined trabeculotomy and trabeculectomy. Patients were examined preoperatively and on the first postoperative day with multiple postoperative follow-up visits within 12 months after surgery. Examination included measurements of intraocular pressure (IOP), corneal diameter, and axial length, bleb evaluation, and funduscopy. Ultrasound biomicroscopy of bleb (bleb presence, wall reflectivity, and scleral route visibility) was done at 1, 3, and 6 months and the last follow-up visit. Any complication was recorded. Data analysis was performed using paired-samples t test. Mean patient age was 5.7 ± 5.69 months. Mean duration of follow-up was 10.05 ± 1.15 months. Mean preoperative IOP was 25.9 ± 3.08 mm Hg with 1.75 ± 0.55 IOP-lowering medications and mean final postoperative IOP was 17.7 ± 3.51 mm Hg with 0.55 ± 0.69 IOP-lowering medications. Overall success at last follow-up was 80%. None of the patients experienced systemic or ocular complication related to OculusGen. By the 6th month, complete Ologen degradation was evident in all cases. The short-term preliminary results of this study indicate that the combined trabeculotomy and trabeculectomy with Ologen implantation could potentially provide a safe and effective procedure in the infantile age group but longer duration of follow-up in larger number of patients is needed.

Measurement of White-to-White Distance Using Pentacam Scheimpflug Imaging versus IOLMaster

Purpose The aim of this study was to assess white-to-white (WTW) horizontal corneal diameter using Pentacam versus IOLMaster and determine whether the two instruments were interchangeable. Patients and methods Twenty eyes were included in this prospective clinical study conducted in I-care Eye Centre, Alexandria. Measurement of WTW horizontal corneal diameter was taken using Pentacam (internal and external measurements) and IOLMaster. Results The mean WTW measured using IOLMaster was 11.66 ± 0.27 mm, ranging from 11.30 to 12.30 mm. The mean WTW externally using Pentacam was 11.93 ± 0.43 mm, ranging from 11.01 to 12.66 mm. The mean WTW internally using Pentacam was 11.20 ± 0.39 mm, ranging from 10.56 to 11.93 mm. The diameters measured using IOLMaster were significantly less than that measured using Pentacam externally and significantly more than that measured using Pentacam internally. There was no correlation between WTW measured using the two machines. Conclusion Although horizontal corneal diameter (WTW) can be measured using Pentacam or IOLMaster, WTW measurement is significantly different between the two instruments and they should not be used interchangeably. Pentacam measurement depends on manual placement of calipers on the Scheimpflug digital image.

Measurement of Corneal Diameter Using Smart Phone Technology

Purpose: To compare horizontal white-to-white (WTW) corneal diameter measurements in children with the MultiMeasureTM iPhone application versus a caliper and evaluate the repeatability of MultiMeasureTM. Methods: This prospective, comparative pilot study enrolled 20 children. The horizontal WTW diameter was measured with calipers with the patient in primary gaze (caliper group). Subsequently, corneal photography was performed with the iPhone in primary gaze (primary group) and with a 20° head turn (HT group). MultiMeasureTM was used to measure WTW. To evaluate repeatability of MultiMeasureTM, WTW was measured in 15 children from a clinic while awake (repeatability group) in primary gaze and with a 20° head turn. Three measurements were performed for all patients. Statistical significance was indicated by p<0.05. Results: The mean age of the sedated patients was 8.3 years (range, 2 to 15 years). The mean WTW was 11.68 ± 0.41 mm, 11.85 ± 0.28 mm and 11.34 ± 0.47 mm in the caliper, primary and HT groups respectively. There was a statistically significant difference between measurements in the caliper and HT groups only (p=0.006). Inter-test variability was not statistically significant different (p=0.45 primary group, p=0.37 HT group, p=0.37 caliper group). The mean age of 15 patients in the repeatability group was 7.6 years (range, 3 to 15 years). In the repeatability group, there was a statistically significant mean difference of 0.36 mm between the repeatability group in primary gaze versus head turned (p=0.001). Conclusion: The smart phone application was a fast, convenient, non-contact, repeatable method for measuring the corneal diameter in children in primary gaze.

Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA.

Effect of corneal contact lens wear on healing time and comfort post LGK for treatment of SCCEDs in boxers.

To determine whether dogs with spontaneous chronic corneal epithelial defects (SCCEDs) would heal faster and with an improved comfort score following linear grid keratotomy (LGK) combined with corneal contact lens (Acrivet(™) ) wear when compared to dogs having the LGK procedure alone. Prospective study. Twenty-seven boxer dogs (27 eyes) diagnosed with a SCCEDs were enrolled in the study. A LGK was performed on all dogs under dexmedetomidine and butorphanol sedation. Fourteen eyes were randomly assigned to receive a corneal contact lens. The dogs were evaluated typically at 7, 10, and 14 days or until the ulceration was healed. Client surveys were completed by the owners to subjectively assess comfort level and contact lens retention. Statistical analyses were performed utilizing generalized linear models and survival analysis with the Wilcoxon-Gehan test to evaluate group differences. All ulcers healed after the LGK procedure. Dogs with bandage contact lenses had a statistically significant (P = 0.035) decrease in median healing time (7 days (95% CI [7,9]) compared to those without contact lenses (10 days (95% CI [7,12])). There was no difference in subjective comfort score between treatment groups. Early contact loss occurred in 28.6% (95% CI [8.4%, 58.1%]) of dogs. All of the Acrivet(™) ruler corneal measurements agreed to within 1 mm (95% CI [87.2%, 100%]) of the Jameson caliper measurements of horizontal corneal diameter. The use of corneal bandage contact lenses significantly decreased median healing time although there was no effect on subjective comfort score. The Acrivet(™) ruler measurements were accurate in determining corneal diameter and therefore contact lens size.

Ultrasound biomicroscopy as a diagnostic tool in infants with primary congenital glaucoma.

PurposeStudying the role of ultrasound biomicroscopy (UBM) in detection of anterior segment changes in infants with primary congenital glaucoma (PCG).MethodsCross-sectional study that included 25 eyes of 15 patients suffering from PCG and a control group of 15 eyes of ten age- and sex-matched participants. Diagnosis of PCG was based on clinical data (intraocular pressure, corneal diameter, fundus examination and amplitude-modulation scan measurement of axial length). UBM examination was done for all participants for measurement of central corneal thickness, anterior chamber depth, lens thickness, iris thickness (measured 2 mm from the iris root and again at the thickest point near the pupil), zonular length, posterior chamber depth, and angle of anterior chamber. Qualitative evaluation was done for abnormal angle membranes, iris insertion level, and ciliary processes position and configuration.ResultsMean age ± standard deviation was 10.32±3.59 months in the study group and 14.54±5.9 months in the control group. The central corneal thickness, anterior chamber depth, zonular length, and angle of anterior chamber were significantly larger in the study group than in the control group, with mean values 700±190 μm, 3.55±0.32 mm, 1.02±0.15 mm, and 58.47°±5.57°, respectively. The posterior chamber depth had a mean of 0.33±0.06 mm, which was significantly smaller than that of the control group. In the study group, the mean iris thickness 2 mm from the iris root was 0.32±0.04 mm, the mean iris thickness at the thickest point near the pupil was 0.38±0.08 mm, and the mean lens thickness was 3.32±0.18 mm. These three parameters were smaller than the control group but the difference was insignificant. Loss of normal iris configuration was detected in all eyes of the study group. Anterior iris insertion was detected in 56% of the eyes in the study group, and abnormal angle membrane was found in 12%.ConclusionUBM is a useful tool for detection of anterior segment changes in PCG, which is helpful especially in cases with opaque cornea or cases with borderline clinical findings.

Pediatric glaucoma: current perspectives

Childhood glaucoma is a heterogeneous group of severe pediatric conditions often associated with significant visual loss and characterized by elevated intraocular pressure (IOP) and optic-disk cupping. Successful IOP control is crucial but challenging and most often achieved surgically, with medical therapy playing a supportive role. There are many classifications of childhood glaucoma, but they can simply be divided into primary, in which a developmental abnormality of the anterior chamber angle only exists, and secondary, in which aqueous outflow is reduced due to independent mechanisms that secondarily impair the function of the filtration angle. The worldwide prevalence of childhood blindness ranges from 0.03% in high-income countries to 0.12% in undeveloped countries. The majority of cases do not have an identified genetic mutation and, where the mutation is known, the genes often account for only a small proportion of cases. Several pathogenetic mechanisms are known to contribute to the development of childhood glaucoma. Whatever the cause, it results in a reduced aqueous outflow at the level of the trabecular meshwork. Age of onset and magnitude of the elevated IOP largely determine the clinical manifestation the high variability of clinical manifestations. Glaucoma from any cause in a neonate and infant is characterized by the classic triad of epiphora, photophobia, and blephar- ospasm, and could be associated with eye enlargement (buphthalmos) and Haab striae. The eye examination, usually performed under general anesthesia, includes: tonometry, anterior-segment examination, gonioscopy, corneal diameter and axial length measurement, dilated fundoscopy with optic-nerve-head evaluation. Medical therapy, considering the high frequency of side effects, is generally used as temporizing IOP-lowering treatment before surgery or as adjuvant treatment postoperatively in case of partially successful procedures for refractory glaucomas. Surgery is the nodal point of the management of refractory childhood glaucoma, so it is crucial to opt for a

Analysis of the horizontal corneal diameter, central corneal thickness, and axial length in premature infants.

To determine the horizontal corneal diameter, central corneal thickness, and axial length in premature infants. Infants with a birth weight of less than 2,500 g or with a gestation period of less than 36 weeks were included in the study. Infants with retinopathy of prematurity (ROP) were allocated to Group 1 (n=138), while those without ROP were allocated to Group 2 (n=236). All infants underwent a complete ophthalmologic examination, including corneal diameter measurements, pachymetry, biometry, and fundoscopy. Between-group comparisons of horizontal corneal diameter, central corneal thickness, and axial lengths were performed. Independent sample t-tests were used for statistical analysis. Data was obtained from 374 eyes of 187 infants (102 female, 85 male). The mean gestational age at birth was 30.7 ± 2.7 weeks (range 25-36 weeks), the mean birth weight was 1,514 ± 533.3 g (range 750-1,970 g), and the mean postmenstrual age at examination was 40.0 ± 4.8 weeks. The mean gestational age and the mean birth weight of Group 1 were statistically lower than Group 2 (p<0.05). There were no significant differences in horizontal corneal diameter, central corneal thickness, and axial length between the two groups (p>0.05). The presence of ROP in premature infants does not alter the horizontal corneal diameter, central corneal thickness, or axial length.

Correlations between different tonometries and ocular biometric parameters in patients with primary congenital glaucoma

To identify the correlation between the difference of intraocular pressure measurements (IOP) obtained using the Goldmann applanation tonometer (GAT) and three others tonometers (Handheld applanation tonometer - HAT, Dynamic contour tonometer - DCT and Tono-Pen®) with biometric characteristics (corneal diameter, pachymetry, keratometry and axial length) in patients with congenital glaucoma. A cross-sectional study was performed on 46 eyes from 46 patients with congenital glaucoma. IOP measurements were obtained in all patients using GAT, HAT, DCT and Tono-Pen®. Keratometry, pachymetry, biometry and corneal diameter measurements were performed after the IOP measurement. The order of the tonometries was randomized. The correlations between the differences of IOP values of GAT and the other tonometers (Delta-IOP), and the different biometric parameters were studied. Tono-Pen® Delta IOP revealed moderate positive correlation to keratometry (r=0.41, p=0.004). The other Delta-IOPs showed no correlation with any of the biometric characteristics evaluated. IOP differences between GAT (gold standard) and GAT, HAT, DCT or Tono-Pen tonometers seem not to correlate with majority of ocular biometric characteristics. The only exception was the keratometry, which correlated in a positive and moderate way with Tono-Pen® Delta-IOP. This result suggests that the differences of IOP values of Tono-Pen® and GAT increase with the steepness of the cornea.

Factors Affecting Corneoscleral Topography

To evaluate factors affecting corneoscleral profile (CSP) using anterior segment optical coherence tomography (AS-OCT) in combination with conventional videokeratoscopy. OCT DATA WERE COLLECTED FROM 204 SUBJECTS OF MEAN AGE 34.9 YEARS (SD: ±15.2 years, range 18-65) using the Zeiss Visante AS-OCT and Medmont M300 corneal topographer. Measurements of corneal diameter (CD), corneal sagittal height (CS), iris diameter (ID), corneoscleral junction angle (CSJ), and scleral radius (SR) were extracted from multiple OCT images. Horizontal visible iris diameter (HVID) and vertical palpebral aperture (PA) were measured using a slit lamp graticule. Subject body height was also measured. Associations were then sought between CSP variables and age, height, ethnicity, sex, and refractive error. Significant correlations were found between age and ocular topography variables of HVID, PA, CSJ, SR, and ID (P < 0.0001), while height correlated with HVID, CD, and ID, and power vector terms with vertical plane keratometry, CD, and CS. Significant differences were noted between ethnicities with respect to CD (P = 0.0046), horizontal and vertical CS (P = 0.0068 and P = 0.0095), and horizontal ID (P = 0.0010). The same variables, with the exception of vertical CS, also varied with sex; horizontal CD (P = 0.0018), horizontal CS (P = 0.0018), and ID (P = 0.0012). Age accounted for the greatest variance in topography variables (36%). Age is the main factor influencing CSP; this should be taken into consideration in contact lens design, IOL selection, and in the optimization of surgical procedures. Ocular topography also varied with height, sex, ethnicity, and refractive error.

Pilot Study for OCT Guided Design and Fit of a Prosthetic Device for Treatment of Corneal Disease.

Purpose. To assess optical coherence tomography (OCT) for guiding design and fit of a prosthetic device for corneal disease. Methods. A prototype time domain OCT scanner was used to image the anterior segment of patients fitted with large diameter (18.5–20 mm) prosthetic devices for corneal disease. OCT images were processed and analyzed to characterize corneal diameter, corneal sagittal height, scleral sagittal height, scleral toricity, and alignment of device. Within-subject variance of OCT-measured parameters was evaluated. OCT-measured parameters were compared with device parameters for each eye fitted. OCT image correspondence with ocular alignment and clinical fit was assessed. Results. Six eyes in 5 patients were studied. OCT measurement of corneal diameter (coefficient of variation, CV = 0.76%), cornea sagittal height (CV = 2.06%), and scleral sagittal height (CV = 3.39%) is highly repeatable within each subject. OCT image-derived measurements reveal strong correlation between corneal sagittal height and device corneal height (r = 0.975) and modest correlation between scleral and on-eye device toricity (r = 0.581). Qualitative assessment of a fitted device on OCT montages reveals correspondence with slit lamp images and clinical assessment of fit. Conclusions. OCT imaging of the anterior segment is suitable for custom design and fit of large diameter (18.5–20 mm) prosthetic devices used in the treatment of corneal disease.

Severe visual impairment and blindness in infants: causes and opportunities for control.

Childhood blindness has an adverse effect on growth, development, social, and economic opportunities. Severe visual impairment (SVI) and blindness in infants must be detected as early as possible to initiate immediate treatment to prevent deep amblyopia. Although difficult, measurement of visual acuity of an infant is possible. The causes of SVI and blindness may be prenatal, perinatal, and postnatal. Congenital anomalies such as anophthalmos, microphthalmos, coloboma, congenital cataract, infantile glaucoma, and neuro-ophthalmic lesions are causes of impairment present at birth. Ophthalmia neonatorum, retinopathy of prematurity, and cortical visual impairment are acquired during the perinatal period. Leukocoria or white pupillary reflex can be cause by congenital cataract, persistent hyperplastic primary vitreous, or retinoblastoma. While few medical or surgical options are available for congenital anomalies or neuro-ophthalmic disorders, many affected infants can still benefit from low vision aids and rehabilitation. Ideally, surgery for congenital cataracts should occur within the first 4 months of life. Anterior vitrectomy and primary posterior capsulotomy are required, followed by aphakic glasses with secondary intraocular lens implantation at a later date. The treatment of infantile glaucoma is surgery followed by anti-glaucoma medication. Retinopathy of prematurity is a proliferation of the retinal vasculature in response to relative hypoxia in a premature infant. Screening in the first few weeks of life can prevent blindness. Retinoblastoma can be debulked with chemotherapy; however, enucleation may still be required. Neonatologists, pediatricians, traditional birth attendants, nurses, and ophthalmologists should be sensitive to a parent’s complaints of poor vision in an infant and ensure adequate follow-up to determine the cause. If required, evaluation under anesthesia should be performed, which includes funduscopy, refraction, corneal diameter measurement, and measurement of intraocular pressure.

Anisometropic amblyopia: Axial length versus corneal curvature in children with severe refractive imbalance

To define the ocular parameters associated with anisometropic ambylopia in children with severe hyperopia, myopia, or astigmatism in 1 eye. Anisometropic and fellow eyes of 13 children, ages 7-8, with anisometropia >3.0 D and amblyopia without strabismus or other visually significant ocular pathology were studied. Axial length, corneal curvature, anterior chamber depth, and corneal diameter measurements of amblyopic and fellow eyes were obtained using the IOL Master (Carl Zeiss Meditec, Dublin, CA). Comparing amblyopic eyes with unaffected fellow eyes as reference, patients with anisohyperopia had shorter axial lengths by an average of 1.49 mm (p = 0.001), and patients with anisomyopia had longer axial lengths by an average of 2.26 mm. Corneal astigmatism was the source of amblyogenic refractive error in 1 child. In children with anisometropic amblyopia, interocular differences in spherical refractive error was attributed to axial length with no differences in corneal curvature, whereas theanisoastigmatism observed in 1 case was attributed to asymmetric corneal curvature.

Ophthalmic Examination Findings in A Captive Colony of Western Gray Kangaroos (Macropus fuliginosus)

Complete ophthalmic examination of a mob of western gray kangaroos (Macropus fuliginosus) was performed under chemical restraint. Examination included intraocular pressure (IOP) measurement by rebound and applanation tonometry, fluorescein staining, corneal diameter measurement, slit-lamp biomicroscopy and indirect funduscopy. The corneal diameters had a mean of 19.52 mm, SD 2.16 mm, 95% confidence interval (CI) 18.71-20.32 mm. Ocular abnormalities were noted in 4/8 (50%) of examined kangaroos. Intraocular pressure as estimated by rebound tonometry was 9.00 mm Hg with a 25-75% quartile range of 6.5-10.75 mm Hg and a minimum-maximum range of 5.00-23.00 mm Hg. Intraocular pressure as estimated by applanation tonometry was 11.50 mm Hg with a 25-75% quartile range of 10.00-17.00 mm Hg and a minimum-maximum range of 9.00-20.00 mm Hg. This is the first report of ocular examination findings in a mob of captive western gray kangaroos and provides ranges and values for tonometry and corneal diameter.