Eye Laterality Research Articles

Profile and Predictors of Normal Ganglion Cell–Inner Plexiform Layer Thickness Measured with Frequency-Domain Optical Coherence Tomography

To describe the profile and identify the predictors of the ganglion cell-inner plexiform layer (GCIPL) thickness measured with frequency-domain optical coherence tomography (FD-OCT) in normal eyes. Two hundred eighty-two normal subjects underwent macular and optic disc scanning in both eyes with Cirrus high-definition (HD)-OCT (Carl Zeiss Meditec, Dublin, CA). Linear regression analyses were performed to determine the association between GCIPL thickness and age, sex, ethnicity (Europeans, Africans, Hispanics, Asians, and Indians), eye laterality, refraction, intraocular pressure, axial length, central corneal thickness, mean retinal nerve fiber layer (RNFL) thickness, disc and rim areas, cup-to-disc area, vertical and horizontal cup-to-disc diameter ratios, vertical rim thickness, and OCT signal strength. The mean (±SD) age was 46.2 ± 16.9 years (range, 18-84 years). The mean and minimum GCIPL thicknesses (±SD) were 82.1 ± 6.2 and 80.4 ± 6.4 μm, respectively. There were significant differences in GCIPL thickness between macular sectors (P < 0.05), except between the superotemporal and inferonasal sectors (P = 0.63). The superonasal sector had the thickest and the inferior had the thinnest GCIPL. The GCIPL of the superior hemisphere was thicker than that of the inferior, and the nasal sector GCIPL was significantly thicker than the temporal one (P < 0.001). The average GCIPL did not differ between male and female subjects (P = 0.16) after adjustment for axial length and between ethnic groups (P = 0.41) after adjustment for age, axial length, and RNFL thickness. Significant predictors of mean GCIPL thickness were average RNFL thickness (β = 0.37, P < 0.001), age (β = -0.083, P < 0.001), axial length (β = -0.87, P = 0.001), and male sex (β = -1.62, P = 0.005). The independent factors associated with thinner GCIPL include thinner RNFL, older age, longer ocular axial length, and being male. Although the magnitude of the effect of age, axial length, and sex are small, these factors should be taken into account when interpreting Cirrus HD-OCT-based GCIPL thickness measurements.

Laterality Preference and Cognition: Cross-Syndrome Comparison of Patients with Trisomy 21 (Down), del7q11.23 (Williams–Beuren) and del22q11.2 (DiGeorge or Velo-Cardio-Facial) Syndromes

We report on a cross-syndrome comparison of hand, foot, eye and ear laterality in three groups of individuals with different genetic disorders (trisomy 21, del7q11.23, and del22q11.2) to test the relationship between atypical laterality and intellectual disability. These groups were compared to a group of typically developing persons. Hand, foot, eye and ear laterality was assessed using item tasks, conducted twice, and Bishop's card-reaching test. Ordering of the mean IQ score for each of the three groups was as follows: trisomy 21<del7q11.23<del22q11.2. We observed the same ordering as for IQ, particularly in mixed handedness, degree of laterality, hand and foot consistency. The existence of a cognitive threshold, below which lateral preference is atypical, advocates for a causal link between cognition and laterality in those with low IQ although unknown other factors underlying both could determine this association.

Central and peripheral intraocular pressure measured by a rebound tonometer

Purpose:We investigated at which corneal region the intraocular pressure as measured by the Icare® rebound tonometer (Finland Oy, Espoo, Finland) (hereinafter referred to as IC) was closest to the intraocular pressure as measured by the Goldmann applanation tonometer (hereinafter referred to as GT). We also investigated which parameters would be best for preparing the most suitable model for predicting GT.Methods:A total of 102 normal eyes in 102 subjects were enrolled. IC measurements were carried out at the central, superior, inferior, temporal, and nasal regions of the cornea (ICC, ICS, ICI, ICT, and ICN, respectively), followed by GT calculations. Differences between GT and IC were analyzed using the Bland–Altman method. Stepwise multiple regression analysis was performed using GT as the objective variable, and age, laterality of eye, spherical equivalent refractive error, corneal radius, axial length, central corneal thickness, GT, ICC, ICS, ICI, ICT, and ICN as the explanatory variables.Results:IC was higher than GT at all of the corneal regions, but the region with the least bias was ICC, followed by ICT. In the multiple regression analysis, the following prediction formula was calculated: GT = (0.445 × ICC) + (0.198 × ICN) + 3.022. When ICC was excluded from the explanatory variables, ICT had the highest partial correlation coefficient with GT.Conclusion:ICC was closest to GT, but GT could be explained better by adding ICN to the prediction model. Moreover, in instances where ICC cannot be calculated or where reliability is clearly poor due to abnormal ocular rigidity, ICT was the closest to GT measured in the central corneal region.

A case of lattice corneal dystrophy due to L527R mutation in the TGFBI gene with asymmetric corneal opacity in eye laterality

A case of lattice corneal dystrophy due to L527R mutation in the TGFBI gene with asymmetric corneal opacity in eye laterality

Clinical observations of macular hole with and without retinal detachment in high myopic eyes

To study the clinical features and the pathogenesis of macular hole with and without retina detachment (RD) in high myopic eyes. It was a retrospective series case study. The charts of high myopic patients with macular hole at our hospital from June 2006 to February 2007 were retrospectively reviewed and analyzed. Patients were divided into two groups (the RD group and non-RD group) depending on the presence of RD or not. Their clinical data and optic coherence tomography (OCT) results were further analyzed. SPSS 13.0 was used for the statistic analysis. When comparing the quantitative aspects like age, axial length and refraction, t-test was used. Categorical data, such as sex ratio, occurrence of vitreous traction, posterior staphyloma and retinoschisis were compared by using χ(2) test. Fisher's test was used in comparing eye laterality, incidence of white hole, visual acuity and posterior vitreous detachment (PVD). During this period, there were 43 patients fitting the including criteria. Among them, 36 patents (37 eyes) were in the RD group and 7 patients (7 eyes) in the no-RD group. In the RD group, the average age was 56.1, 24.3% of them (9/37) were male; percentage of left and right eyes was (11/37) and 70.3% (26/37), respectively; average refraction was (-8.9 ± 2.2) D; average axial length was (28.7 ± 2.0) mm. Visual acuity was ≤ 0.05 (72.2%) in 26 eyes and 0.05 - 0.2 (27.8%) in 10 patients. The incidence of complete and non-complete PVD was 89.2% (33/37) and 10.8% (4/37), respectively. White hole presented in 35.1% (3/37) patients. Vitreous traction and retinoschisis presented in 27.0% (10/37) and 35.1% (13/37) patients, respectively. In the non-RD group, the average age was 47.6; 16.7% of them (1/7) were male; left and right eyes were involved in 42.9% (3/7) and 57.1% (4/7), respectively. Average refraction was (-9.0 ± 1.9) D; average axial length was (28.9 ± 1.5) mm. Vision acuity was ≤ 0.05 in 3 patients (42.9%); between 0.05 - 0.2 in 3 eyes (42.9%) and ≥ 0.2 in 1 eye (14.3%). Incidence of complete and non-complete PVD was 85.7% (6/7) and 14.3% (1/7), respectively. White hole was observed in 14.3% (1/7) patients; 42.9% (3/7) patients were accompanied with vitreous traction and 71.4% (5/7) with retinoschisis. B-scan ultrasonography showed posterior staphyloma in all 44 eyes. The results of statistical analysis showed that the gender (χ(2) = 0.008) and eye laterality (χ(2) = 0.449) as well as refraction (t = 0.193), axial length (t = -0.25) and visual acuity (χ(2) = 4.509) of these two groups were similar (P > 0.05). The incidences of vitreous traction (χ(2) = 0.709), white hole (χ(2) = 1.179), PVD (χ(2) = 0.071) and retinoschisis (χ(2) = 3.207) were also similar (P > 0.05). But the age of the non-RD group is significantly younger than the RD group (t = 1.66, P < 0.05). Various pathogenesis may involved in the occurrence of retinal detachment in highly myopic eyes with macular hole. Further study is required to improve our understanding of this entity.

Laterality of Amblyopia

To determine the frequency of unilateral amblyopia in right versus left eyes among children younger than 18 years. Analysis of data collected in randomized clinical trials conducted by the Pediatric Eye Disease Investigator Group. The laterality of the amblyopic eye was analyzed in 2635 subjects younger than 18 years who participated in 9 multicenter prospective, randomized treatment trials. Eligibility criteria for these clinical trials included unilateral amblyopia associated with strabismus, anisometropia, or both, with visual acuity between 20/40 and 20/400. Logistic regression was used to assess the association of baseline and demographic factors with the laterality of amblyopia. Among subjects with anisometropic amblyopia (with or without strabismus), amblyopia was present more often in left than right eyes, with a relative prevalence of 59% in left eyes (95% confidence interval, 57% to 62%; P < .001 from a test of proportion, 50%). However, among subjects with strabismic-only amblyopia, there was no laterality predilection (relative prevalence of 50% in left eyes; 95% confidence interval, 47% to 54%; P = .94). Anisometropic amblyopia, with or without strabismus, occurs more often in left eyes than right eyes. This finding of amblyopia laterality may be related to microtropia, sighting dominance, or other forms of ocular dominance; developmental or neurological factors; laterality in the development of refractive error; or a combination thereof.

Ocular wavefront analysis and contrast sensitivity in eyes implanted with AcrySof IQ or AcrySof Natural intraocular lenses

This study aimed to compare ocular wavefront aberrations for pupil diameters of 4 mm and 6 mm, and contrast sensitivity, in eyes with AcrySof IQ and AcrySof Natural intraocular lenses (IOLs). Sixty eyes of 60 patients were enrolled in this prospective randomized study. After phacoemulsification the eyes received either AcrySof IQ SN60WF or AcrySof Natural SN60AT IOLs. One month after surgery, all patients underwent complete ophthalmological examination including corneal topography, wavefront analysis for pupil diameters of 4 mm and 6 mm, and contrast sensitivity measurements with the CSV 1000E instrument under photopic and mesopic conditions with and without glare. There was no statistically significant difference between groups in age, sex or other preoperative ocular characteristics (p > 0.05). Patients with AcrySof IQ IOLs had higher contrast sensitivity at 6 c.p.d. under photopic conditions, at 6 c.p.d. and 18 c.p.d. under mesopic conditions, and at 6 c.p.d., 12 c.p.d. and 18 c.p.d. under mesopic conditions with glare (p < 0.05). Corneal spherical aberration was 0.273 ± 0.074 μm in the AcrySof Natural group and 0.294 ± 0.086 μm in the AcrySof IQ group (p = 0489). Ocular spherical aberration was 0.362 ± 0.141 μm and 0.069 ± 0.043 μm (p < 0.001) for 6-mm diameter pupils and 0.143 ± 0.091 μm and 0.017 ± 0.016 μm (p < 0.001) for 4-mm diameter pupils, with AcrySof Natural and AcrySof IQ IOLs, respectively. There were no significant differences in other higher-order aberrations between the groups (p > 0.05). Aspherical AcrySof IQ IOLs significantly reduced spherical aberration for pupil diameters of both 4 mm and 6 mm and also improved contrast sensitivity more than spherical AcrySof Natural IOLs, especially in mesopic conditions.

Incidence of intraoperative complications in cataract surgery performed by left-handed residents

To compare the incidence of intraoperative complications during cataract surgery performed by left-handed and right-handed residents and to find predictor variables for complications in resident-performed surgery. Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA. This retrospective chart review comprised cataract extractions performed by postgraduate fourth-year residents from July 1, 2001, to June 30, 2006. The incidence of posterior capsule tear and vitreous loss were the main outcomes. Univariate and multivariate logistic analyses incorporated the variables of patient age and sex; laterality of surgical eye; presence of diabetes mellitus, glaucoma, or age-related macular degeneration; history of vitrectomy; axial length; pseudoexfoliation; small pupils; white cataract; posterior polar cataract; handedness of resident; and academic quarter during which surgery occurred. Left-handed residents performed 170 (9.8%) of the 1730 surgeries. The incidence of posterior capsule tear and vitreous loss was significantly lower in surgeries performed by left-handed residents than in those performed by right-handed residents (P = .03 and P<.001, respectively). Multivariate logistic analysis showed that resident right-handedness and older patient age were predictive of an increased incidence of posterior capsule tear and vitreous loss. A small pupil was predictive of an increased incidence of vitreous loss. The incidence of posterior capsule tear and vitreous loss was significantly lower in cataract surgeries performed by left-handed residents. Handedness and patient age were significant predictor variables for these complications.

Topical Anesthesia versus Sub-Tenon Block for Cataract Surgery: Surgical Conditions and Patient Satisfaction

To compare the surgical conditions and complications and patient and surgeon satisfaction in cataract surgery by phacoemulsification under topical anesthesia (TA) versus sub-Tenon block (STB). Prospective randomized comparative blind study, without placebo control. Patient satisfaction evaluated by the Iowa Satisfaction with Anesthesia Scale (ISAS). The authors prospectively enrolled 59 patients (61% female) in the study, who were randomized into groups: 26 in the TA group and 33 in the STB. There was no statistically significant difference between the groups in terms of age, sex, waiting time for surgery, ASA (American Society of Anesthesiologists) state, eye laterality, cataract density, pupillary dilation, or surgery duration, but patient collaboration was better in the STB group. We found a mean 2.2 mmHg post-anesthetic rise in intraocular pressure in the STB group, with normalization at 24 hours, and no rise in the TA group. Subconjunctival hemorrhage and chemosis were more prevalent in the STB group, and the improvement of visual acuity was similar in both groups. Subjective satisfaction with the anesthetic technique, both for the surgeon and for the patient, was more elevated in the STB group. The final ISAS scores were 1.87 in the TA group and 2.71 in the STB (p<0.005). The data indicate that more significant anesthesia and analgesia was achieved with the STB, leading to more favorable surgical conditions and enhanced patient and surgeon satisfaction.

Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype

Purpose To quantify the difference between recognition (letter) and resolution (Landolt) visual acuity (VA) in a group of normally sighted subjects. Is it reasonable to assume that the two acuity measures are clinically equivalent? Methods A pair of 6 m acuity test charts was produced: one comprised letters and the other Landolt broken rings. Construction of both charts conformed to the logMAR design format. Monocular VA was determined for the dominant eye of 300 screened and normally sighted optometric patients aged 16 to 40, each wearing an optical refractive (spectacle) correction. Results Letter acuity was superior to Landolt acuity ( P≤0.0001). The mean paired acuity difference was -0.041 logMAR (standard deviation 0.034): the 95% limits of agreement were ±0.067 logMAR units or ±3.3 chart optotype. Repeatability was high and similar for each chart type (±2.1 and ±2.4 optotype for letter and Landolt, respectively). Gender, test sequence, and laterality of the dominant eye (left or right) were each non-statistically significant variables. Conclusions For normally sighted subjects wearing an optimal refractive correction, a bias was recorded in favour of recognition over resolution acuity: the clinical difference amounted to approximately 40% of one logMAR chart line, with similar high repeatability for either chart optotype. We conclude that the assumption of clinical equivalence between letter and Landolt acuity is reasonable under optimum test conditions.

Long-term Outcomes of Ahmed Glaucoma Valve Implantation in Refractory Glaucomas

To evaluate the long-term efficacy of intraocular pressure (IOP) reduction and complications of Ahmed glaucoma valve (AGV) implantation (New World Medical, Inc, Rancho Cucamonga, California, USA) in refractory glaucoma. Retrospective cohort study. Retrospective medical records from 64 patients (78 eyes) with refractory glaucoma who underwent AGV implantation with a minimum of three years of follow-up were reviewed. Data regarding age, gender, race, eye laterality, specific glaucoma diagnosis, best-corrected visual acuity (BCVA), number of medications, IOP, visual fields, surgical complications, and follow-up interval were collected from all visits and were analyzed. The primary outcome measure was cumulative probability of success defined as IOP of less than 21 mm Hg and of 5 mm Hg or more with a minimum of 15% reduction from baseline IOP, without additional glaucoma surgery or loss of light perception. Secondary outcomes included IOP and number of medications at three, six, 12, 24, 36, 48, and 60 months after surgery, surgical complications, and final BCVA. The cumulative probability of success was 80% and 49% at one and five years, respectively. IOP was reduced from a mean of 30.4 +/- 10.7 mm Hg to 17.0 +/- 5.0 mm Hg at 12 months and 15.9 +/- 3.0 mm Hg at 60 months (P < .001). The number of medications decreased from 3.2 +/- 1.0 medications at baseline to 1.6 +/- 0.4 at 12 months and 2.1 +/- 0.2 at 60 months (P < .001). Prior glaucoma surgery and the silicone type of AGV were statistically significant risk factors for failure (P < .001). Approximately 50% of single-plate AGV implantations in refractory glaucoma were considered successful after five years of follow-up. Prior glaucoma surgery was a statistically significant risk factor for failure.

Embryogenesis and Expression Profiles ofcharonand Nodal-Pathway Genes in Sinistral (Paralichthys olivaceus) and Dextral (Verasper variegatus) Flounders

Although it is well known that flounder form external asymmetry by migration of one eye at metamorphosis, the control system that forms this asymmetry is unknown. To help elucidate this mechanism, we here describe the embryogenesis and expression profiles of the Nodal-pathway genes in the Japanese flounder, Paralichthys olivaceus. We also perform a comparative study of the laterality of the expression of these genes in sinistral (P. olivaceus) and dextral (Verasper variegatus) flounders. In P. olivaceus, Kupffer's vesicle forms at the 2-somite stage, after which left-sided expression of spaw starts at the 8-somite stage. Left-sided expression of pitx2 occurs in the gut field at the 15-somite to high-pec stages, in the heart field at the 21-somite stage, and in the dorsal diencephalon at the 27-somite to high-pec stages. In response to left-sided pitx2 expression, the heart, gut, and diencephalon begin asymmetric organogenesis at the pharyngula (heart) and the long-pec (gut and diencephalon) stages, whereas the eyes do not show signs of asymmetry at these stages. In both sinistral and dextral flounders, the Nodal-pathway genes are expressed at the left side of the dorsal diencephalon and left lateral-plate mesoderm. Considering these data together with our previous finding that reversal of eye laterality occurs to some extent in the P. olivaceus mutant reversed, in which embryonic pitx2 expression is randomized, we propose that although the Nodal pathway seems to function to fix eye laterality, embryonic expression of these genes does not act as a direct positional cue for eye laterality.

Ocular Torsion in Unilateral Superior Oblique Palsy

Purpose: We evaluated the concordance of laterality of the paretic eye and the torsional eye in unilateral superior oblique palsy showing an inferior oblique overaction. Methods: Thirty-nine patients diagnosed as having a unilateral superior oblique palsy were evaluated for visual acuity, refractive manifestation, ocular movement, prism cover test, and fundus photograph. Of these patients, 32 derived from congenital causes and 7 acquired the condition from trauma. An ocular movement exam was performed to check an inferior oblique overaction, and a fundus photograph was used to measure the ocular torsional amount. Inferior oblique myectomy or recession was performed along with horizontal strabismus surgery. Results: Objective extorsion was presented in paretic eyes of 29 patients (74.4%) and nonparetic eyes of 10 patients (25.6%). The congenital superior oblique palsy patients were divided into two groups by the concordance of laterality of paretic eyes and torsional eyes. In the concordance group of 22 patients, the torsional amount was decreased from +17.69°to +7.98°and inferior oblique overaction from +2.27°to +0.25°after an inferior oblique muscle weakening procedure. In the discordance group of 10 patients, torsional amount was decreased from +16.97°to +8.73°and inferior oblique overaction from +2.50°to +0.21°postoperatively. In acquired oblique palsy patients, all patients showed the concordance of laterality, and the torsional amount was decreased from +16.76°to +8.80°and inferior oblique overaction from +2.5°to +0.21°after inferior oblique weakening procedure. Conclusions: We found that the paretic eye and the torsional eye may not coincide in congenital superior oblique palsy but always coincide in acquired oblique palsy after trauma. After an inferior oblique muscle weakening procedure, ocular torsional amount of paretic or sound eye is decreased in every case.

Cataract surgery in the last decade at University Teaching Hospital, Ilorin, Nigeria

A retrospective study of all the patients admitted to the eye ward of University of Ilorin Teaching Hospital (UITH) between January 1990 and December 2000 was done to determine the prevalence of cataract among them. The demographic data and possible risk factors for cataract as well as the laterality of the blind eye were recorded for each patient. The diagnosis of cataract was based on the patient's history, visual acuity assessment by Snellen chart and morphological changes on ophthalmoscopy and slit-lamp microscopy. Seven hundred and sixty-two (43.1%) of the admitted patients (1,769) had cataract consisting of 411 males (53.9%) and 351 females (46.1%), giving M: F ratio 1.2:1. Cataract cases accounted for 54.5% of all ocular surgeries (n = 1,398). About 10% were below the age of 16 years. Bilateral cases were 78.9%, unilateral 21.1%. The right and left eye was involved in 13.2% and 7.9% cases respectively. Cataract was most common (76.6%) in patients older than 45 years. Other causes were congenital – 4.3%, trauma – 11.4%, secondary – 1.2% and unspecified causes – 6.4%. Though hospital based, the prevalence of cataract might be a reflection of the situation within the community as several factors might have been responsible for the low uptake of surgery. Cataract surgical services should be more accessible to the people. We are unaware of a similar report from this institution since the inception of the department as a tertiary eye center in 1988. Keywords: cataract, prevalence, Ilorin, Nigeria Nigerian Medical Practitioner Vol. 49(6) 2006: 161-163

Laterality in persons with intellectual disability II. Hand, foot, ear, and eye laterality in persons with Trisomy 21 and Williams‐Beuren syndrome

Laterality (hand, foot, ear, and eye) was assessed in participants with Trisomy 21 (62) and Williams-Beuren syndrome (WBS) (39). Handedness was also assessed in a card reaching task. The comparison group included 184 typically developing persons. Two independent age sub-groups were formed: 7 to 10 years old and 11 to 34 years old. We confirmed previous data: individuals with T21 were more frequently left- or mixed-handed than typically developing persons; individuals with WBS had intermediate scores. The two groups with genetic disorders had less right foot preference. Manual and foot inconsistencies characterized both groups with genetic disorders. Cross hand-foot preference was lower in the typically developing group. Differences in IQ levels did not correlate with differences in laterality scores. Overall laterality profiles were not the same in the two groups with genetic disorders: the greatest differences were observed between typically developing persons and persons with Trisomy 21.

Comparison between the Role of Intraoperative Mitomycin C and Doxorubicin in Preventing the Recurrence of Primary Pterygium

Purpose: The purpose of this study was to compare the role of intraoperative mitomycin C (MMC) and doxorubicin in preventing the recurrence of primary pterygium. Materials and Methods: Fifty-six patients including 22 males and 34 females in the age range of 22–55 years (mean age 38.1 years ± 10.7) having primary pterygium of progressive type were randomly divided into two groups. The first group of patients was treated with intraoperative MMC (0.02% for 3 min) and in the second group intraoperative doxorubicin (0.02% for 3 min) was used. The patients were regularly followed until 1 year postoperatively for examining visual acuity, wound condition, adverse events and recurrence of pterygium. Results: The mean age of patients of MMC group was 37.4 ± 11.0 years and of doxorubicin group was 38.8 ± 10.8 years (difference statistically not significant). All these patients had pterygium on the medial side of cornea. The side effects experienced by our patients from the use of these agents were conjunctival hyperemia, conjunctival necrosis, corneal epithelial defect, subconjunctival hemorrhage, episcleritis, increased pain, foreign body sensation, lacrimation, irritation, diminution of vision and photophobia. Recurrence was seen in 4 patients of MMC group (14.3%) and 3 patients of doxorubicin group (10.7%) (difference statistically not significant; χ² = 0.16, p = 0.68). The recurrence of pterygium was not associated with age of patients, laterality of eye involved, amount of encroachment of pterygium over cornea, width of pterygium, preoperative complaints and postoperative adverse events. Conclusions: The two antimitotic agents, MMC and doxorubicin, when used intraoperatively along with primary pterygium excision, had a comparable role both in terms of adverse events and prevention of recurrence of pterygium.

内臓の左右軸形成と変態期の眼の移動との関わり

内臓の左右軸形成と変態期の眼の移動との関わり

Gene expression variation in the adult human retina

Despite evidence that differences in gene expression levels contribute significantly to phenotypic variation across individuals, there has been only limited effort to study gene expression variation in human tissue. To characterize expression variation in the normal human retina, the authors utilized a custom retinal microarray to analyze 33 normal retinas from 19 donors, aged 29 to 90 years. Statistical models were designed to separate and quantify biological and technical sources of variation, including age, gender, eye laterality, gene function, and age-by-gender interaction. Although the majority of the 9406 genes analyzed showed relatively stable expression across different donors (for an average gene the expression level value of 95 out of a 100 individual fell within a 1.23-fold range), 2.6% of genes showed significant donor-to-donor variation, with a false discovery rate of 10%. The mean expression ratio standard deviation was 0.15 ± 0.8, log2, with a range of 0.09 to 0.99. Genes selectively expressed in photoreceptors showed higher expression variation than other gene classes. Gender, age, and other donor-specific factors contributed significantly to the expression variation of multiple genes, and groups of genes with age- or gender-associated expression pattern were identified. These findings show that a significant fraction of gene expression variation in the normal human retina is attributable to identifiable biologic factors. The greater expression variability of many genes central to retinal function (including photoreceptor-specific gene) may be partially explained by the dynamics of the vision process, and raises the possibility that photoreceptor gene expression levels may contribute to phenotypic diversity across normal adult retinas. Additionally, as such diversity may result in different levels of disease susceptibility, exploring its sources may provide insights into the pathogenesis of retinal disease.—Hans E. Grossniklaus Despite evidence that differences in gene expression levels contribute significantly to phenotypic variation across individuals, there has been only limited effort to study gene expression variation in human tissue. To characterize expression variation in the normal human retina, the authors utilized a custom retinal microarray to analyze 33 normal retinas from 19 donors, aged 29 to 90 years. Statistical models were designed to separate and quantify biological and technical sources of variation, including age, gender, eye laterality, gene function, and age-by-gender interaction. Although the majority of the 9406 genes analyzed showed relatively stable expression across different donors (for an average gene the expression level value of 95 out of a 100 individual fell within a 1.23-fold range), 2.6% of genes showed significant donor-to-donor variation, with a false discovery rate of 10%. The mean expression ratio standard deviation was 0.15 ± 0.8, log2, with a range of 0.09 to 0.99. Genes selectively expressed in photoreceptors showed higher expression variation than other gene classes. Gender, age, and other donor-specific factors contributed significantly to the expression variation of multiple genes, and groups of genes with age- or gender-associated expression pattern were identified. These findings show that a significant fraction of gene expression variation in the normal human retina is attributable to identifiable biologic factors. The greater expression variability of many genes central to retinal function (including photoreceptor-specific gene) may be partially explained by the dynamics of the vision process, and raises the possibility that photoreceptor gene expression levels may contribute to phenotypic diversity across normal adult retinas. Additionally, as such diversity may result in different levels of disease susceptibility, exploring its sources may provide insights into the pathogenesis of retinal disease.—Hans E. Grossniklaus

Ocular anisometropia and laterality.

To study the difference in refraction between right and left eyes (anisometropia) in different age groups, look for evidence of eye laterality (more refractive error in one eye) and compare the size of anisometropia in the myopic and emmetropic ranges. The study was based on children in Hong Kong (examined at the age of 6 years and again at the age of 8.5 years) and their parents (aged 26-60 years). In all age groups the difference between right and left eyes in sphere and cylinder was modest, in most cases < or = 0.25 D. In both children and their parents a tendency towards spherical right eye laterality was found in the myopic individuals (p < 0.05). This was not the case with the cylinder. In the 8.5-year-old children and in their parents, the numerical size of spherical anisometropia increased with myopia (p < 0.05 and p < 0.01, respectively). Cylindrical anisometropia did not exhibit such an increase. In Hong Kong children and their parents we found a tendency towards more spherical myopia in right eyes (laterality) in myopic cases. The numerical size of spherical anisometropia also increased in myopia in these groups. Cylindrical anisometropia appeared to be independent of spherical ametropia. In most cases right/left differences in both sphere and cylinder were small and our findings justify the use of data from one eye only in publications on refraction.

Experience with bicanalicular intubation of the lacrimal drainage apparatus combined with conventional external dacryocystorhinostomy

Aim: The aim of this study was to assess the success rate of bicanalicular intubation of lacrimal drainage apparatus in chronic dacryocystitis patients who were at high risk of failure of surgery of dacryocystorhinostomy. Material and methods: A total of 24 patients with chronic dacryocystitis (25 eyes) including 11 males and 13 females (age range 3–80 years) having high risk factors of failure of dacryocystorhinostomy were enrolled. Factors such as previous attacks of acute dacryocystitis, trauma in lacrimal sac region, previously failed dacryocystorhinostomies, formation of false passages in the lacrimal drainage apparatus were considered. Conventional dacryocystorhinostomy followed by bicanalicular intubation of the lacrimal drainage apparatus with Jain metal silicone the lacrimal intubation tube (20–23 gauge) was performed in all these patients. The patients were followed up at weekly intervals for two months, at 6 months and at 1 year post surgery. Results: A total of 25 eyes in 24 patients (including 11 males and 3 females) were operated upon using the technique of bicanalicular intubation of lacrimal drainage apparatus with conventional external dacryocystorhinostomy. The procedure was successfully performed in 22 out of the 25 eyes. Perioperative complications included punctual damage due to recurrent attempts at passing these probes in 2 patients and mild damage to nasal mucosa in 5 patients. The majority of patients did not experience any untoward symptoms from these silicone tubes. However, in three eyes there was felt a mild foreign body sensation and two patients had chronic conjunctival erythema. The tubes could not be retained in two of these three eyes. Additionally, in one eye there was spontaneous extrusion of tubes whilst sneezing 3 months after surgery. All these three eyes had a recurrence of symptoms due to non-retention of the tubes and needed re-operation. On average the tubes were retained for a period of six months before they were spontaneously extruded or removed. Fifteen patients retained the silicone tubes for more than 1 year. The procedure gave a success rate of 76% (19/25 eyes) and these were the eyes in which the tubes had been retained for more than 6 months. The success was not influenced by the age or sex of patient, laterality of eye, aetiology of chronic dacryocystitis, or evidence of bony deformity or abnormality of the sac. Conclusions: Bicanalicular intubation for lacrimal drainage system is a simple, inexpensive and straight forward adjunct to conventional external dacryocystorhinostomy. The procedure is strongly indicated for patients with chronic dacryocystitis who are at high risk of surgical failure. Carefully performed, it gives a 76% success rate and is not influenced by the different variables examined.