Does Surgical Resection of Horizontal Extraocular Muscles Disrupt Ocular Proprioceptors?

Purpose: It has been promoted that disturbance of ocular proprioception may play a role in the pathogenesis of concomitant strabismus and other types of oculomotor anomalies. The aim of the study was to obtain knowledge about how surgical foreshortening of the myotendinous region potentially affects the proprioceptors that resides in this area of the muscles and to test the hypothesis that avoiding disruption of ocular proprioceptors result in a more favorable long term postoperative result. Patients and Methods: The distal end of the lateral and medial rectus muscles from patients with manifest concomitant strabismus with a deviation of ≥15 prism diopters (PD) were collected during strabismus surgery and processed for light microscopy by standard histochemical techniques. Histological analysis served to differentiate between the tissue samples containing pure tendon, versus samples containing the myotendinous junction. Criteria for successful outcome was defined as a residual angle of deviation less than 10 PD. The binocular status of the patient was measured pre- and post-operatively at 6-months of follow-up. Results: Tissue samples from 43 patients (median age 19 years old, range 3-58 years) were collected during surgery. Twenty-six of the samples contained pure tendon, while 17 contained muscle fibres. The evolution of the post-operative result revealed a moderate reduction in the residual angle of deviation in patient-samples containing pure tendon. In contrast, the residual angle of deviation clearly increased in patient-samples containing muscle fibres. The difference between the two groups reached statistical significance after 6 months. Successful outcome was found to be more than three times more likely in cases where surgery was performed in pure tendon, compared to muscle fibres. Conclusion: The current study supports the hypothesis that avoiding disruption of ocular proprioceptors, located in the distal myotendinous region, results in a more favorable postoperative result.

Comparison of Short-Term Effects of Treatment of Accommodative Infacility with Low Plus Addition in Single Vision Rx or Vision Therapy: A Pilot Study.

Purpose: To compare the short-term treatment effect of low plus reading addition (ADD) and home-based vision therapy (VT) in a small group of symptomatic children with accommodative infacility (AIF) being the most significant dysfunction. Methods: Nineteen children, 8 to 12 years of age, with a first-time diagnosis of AIF were consecutively and alternately allocated to treatment with ADD (+0.50 D addition in single vision Rx) or VT (accommodation exercises using Hart Charts) for a period of 6 weeks. Accommodation facility (AF) was measured monocularly (MAF-R, MAF-L) and binocularly (BAF) with +2 D/-2 D flipper and registered in cycles per minute (cpm). Symptoms were graded using the convergence insufficiency symptom survey (CISS). Measurements were compared before and after treatment and between groups using nonparametric statistics (p < 0.05). Results: Ten children were allocated to ADD (median age 9.0 F:5) and 9 to VT (median age 11.0 F:7). Baseline median measurements of MAF-R, MAF-L, BAF and CISS were 3.0, 3.0, 2.2 cpm, and 27.5 points, respectively, for ADD, and 2.0, 2.0, 2.0 cpm, and 27.0 points, respectively, for VT. There were no significant differences between groups at baseline. After 6 weeks of treatment, the median change of MAF-R, MAF-L, BAF and CISS was +5.0, +4.5, +4.7 cpm, and -7.5 points, respectively, for ADD and +8.0, +8.0, +10.0 cpm, and -20.0 points, respectively for VT. All changes within groups were significant. Comparison of groups showed a significantly greater effect of treatment with VT compared to ADD for BAF (p = 0.008) and CISS (p = 0.017). Conclusion: In children with newly diagnosed AIF, treatment with accommodation exercises for 6 weeks gives greater short-term relief of symptoms and improvement of binocular accommodative facility compared to treatment with spectacle single vision correction with a weak plus addition.

Prevalence and Predictors of Ocular Complications in Obstructive Sleep Apnea Patients: A Cross-sectional Case-control Study.

PURPOSE: This study sought to identify the magnitude and the possible risk factors of ocular complications in patients with Obstructive Sleep Apnea (OSA). METHODS: A hospital-based cross-sectional study with a nested case-control design was conducted. Qualifying study subjects were patients who had been diagnosed with moderate to severe OSA (AHI index of ≥ 5, n=80), and control subjects (n=20) who had an AHI index of ≤ 5 ("normal"). Study participants were recruited from Mansoura University Hospital's Sleep Disorders Clinic in Mansoura, Egypt.Selected subjects were assessed for ocular complications at Mansoura Univerity Hospital Ophthalmic Center, (Mansoura), Egypt. An ophthalmic history was recorded, and opthalmic testing was carried out. The testing included unaided visual acuity measurement, refraction, best-corrected visual acuity measurement, slit lamp bio-microscopic evaluation of the anterior segment and anterior segment photography, dilated fundus examination, intraocular pressure measurement, fundus photo, and fluorescein angiography, and visual field assessment. Various tests of OSA symptoms were also monitored, including the AHI, lowest oxygen concentrations and desaturation index plus the overall severity index. . RESULTS: It was found that OSA patients n=28 (35%), n=24 (30%), n=4 (5%) had senile cataract, normal tension glaucoma, and retinal ischemia, respectively, with an overall prevalence of 45%. Additionally, the OSA group had seven times greater risk (OR=7.36, 95%CI: 1.6-33.86) of vision-threatening disorders compared to the controls. OSA patients were observed to be at a greater risk of senile cataract 28 (35%), normal tension glaucoma 24 (30%), retinal ischemia 4 (5%) and conjunctival hyperemia and dry eye (OR=3.77, 95%CI: 1.02-13.95, OR=4.36, 95%CI: 1.26-17.08). Also, multivariate logistic regression analysis testing showed that the lowest oxygen saturation index was the only significant predictor negatively associated with vision-threatening disorders (OR=0.84, 95%CI: 0.75-0.93). CONCLUSION: The risk of vision-threatening and non-threatening ocular disorders is higher among OSA cases. The lowest oxygen saturation index was the only significant predictor of vision-threatening disorders. These findings support the recommendation that a full ophthalmic examination should be carried out on patients with confirmed OSA.

Survey of referrals and medical reports in optometric practices in Norway: midterm findings from a 3-year prospective Internet-based study.

PURPOSE: The increasing demand for primary eye care due to an aging population implicates an enhanced role of optometrists in the communities. The primary objective of this study was to investigate the rate of referrals and returning medical reports between optometrists and health care professionals in Norway. The secondary objectives were to investigate the conformity of diagnoses in referrals and medical reports, the extent of optometric follow-up examinations and the use of ophthalmic diagnostic drugs in optometric practice. MATERIALS AND METHODS: This study is an ongoing prospective electronic survey administered on the Internet between November 2014 and December 2017. Optometrists in private optometric practice are eligible. Participants register data for up to 1 year, including examinations and the use of ophthalmic diagnostic drugs; referrals, including International Classification of Primary Care, second edition (ICPC-2) codes; medical reports, including the ICD-10 codes; and optometric follow-up enquiries. Analysis of agreement between referred and diagnosed conditions was made possible by encoding patients' ID. RESULTS: Seventeen months into the study, 67 optometrists were included (Female: 60%, mean age: 41 years.). There were 49,510 registered examinations (60% general, 28% contact lens, 12% auxiliary). Diagnostic drugs were used in 4% of these and in 14% of the examinations that resulted in a referral. There were 1,779 referrals (97% to ophthalmologists). Top three diagnoses were cataract (36%), glaucoma (11%), and age-related macular degeneration (7%). There were 1,036 returned medical reports, of which 76% could be linked with registered referrals. Diagnostic agreement was observed in 80% of the cases (74% for primary diagnoses). There were only 17 registered cases of optometric follow-ups. CONCLUSION: In Norway, nearly all referrals from optometrists are to ophthalmologists. More than half of these result in a returned medical report. Nonreturned reports do not seem to trigger optometric follow-ups. The diagnostic agreement between referrals and medical reports is high. Diagnostic ophthalmic drugs are used sparsely by optometrists and mostly in relation to referrals.

Depressive symptomatology in tertiary-care glaucoma patients.

OBJECTIVE: To investigate depressive symptomatology among patients with glaucoma and to relate the findings to disease stability. DESIGN: Cross-sectional postal survey. PARTICIPANTS: The study sample consisted of 258 patients out of a pool of 884 respondents to a survey on health and sleep sent to 1809 glaucoma patients registered in a major tertiary glaucoma centre at the Toronto Western Hospital, Toronto, Ont. METHODS: The Center for Epidemiologic Studies Depression Scale questionnaire was mailed along with questions related to demographic information, general health, and sleep quality. Respondents were included if (i) their diagnosis was either primary open-angle glaucoma, normal tension glaucoma, or primary angle-closure glaucoma; (ii) the disease duration was 3 years or more; (iii) clinical examinations were obtained annually; and (iv) perimetric results were reliable. Each patient's condition was classified as stable or progressive on the basis of pointwise decline in visual fields (VFs). RESULTS: The unadjusted odds ratio for depressive symptoms was found to be 0.4 times less (95% CI 0.19-0.88) in patients with progressive VFs (n = 79) than in patients with stable VFs (n = 179). Adjusting for demographic characteristics, general health, psychiatric comorbidity, and ocular factors did not weaken this association. However, it was reduced by the increased severity of VF defects (moderate and severe). CONCLUSIONS: In this sample of tertiary-care patients, depressive symptoms were found to be less common in patients with progressive than with stable VFs when defects were classified as early, but not when they were classified as moderate or severe.

Melatonin in the eye: implications for glaucoma.

Melatonin synthesis occurs in the retina of most animals as well as in humans. Circadian oscillators that control retinal melatonin synthesis have been identified in the eyes of different animal species. The presence of melatonin receptors is demonstrable by immunocytochemical studies of ocular tissues. These receptors may have different functional roles in different parts of the eye. In view that melatonin is a potent antioxidant molecule, it can be effective in scavenging free radicals that are generated in ocular tissues. By this mechanism melatonin could protect the ocular tissues against disorders like glaucoma, age-related macular degeneration, retinopathy of prematurity, photo-keratitis and cataracts. Although an increased intraocular pressure is an important risk factor in glaucoma, other concomitant phenomena like increased glutamate levels, altered nitric oxide metabolism and increased free radical generation seem to play a significant role in its pathogenesis. Data are discussed indicating that melatonin, being an efficient antioxidant with antinitridergic properties, has a promising role in the treatment and management of glaucoma.

Role of melatonin in the eye and ocular dysfunctions.

Melatonin is a ubiquitous molecule and widely distributed in nature, with functional activity occurring in unicellular organisms, plants, fungi, and animals. Several studies have indicated that melatonin synthesis occurs in the retina of most vertebrates, including mammals. The retinal biosynthesis of melatonin and the mechanisms involved in the regulation of this process have been extensively studied. Circadian clocks located in the photoreceptors and retinal neurons regulate melatonin synthesis in the eye. Photoreceptors, dopaminergic amacrine neurons, and horizontal cells of the retina, corneal epithelium, stroma endothelium, and the sclera all have melatonin receptors, indicating a widespread ocular function for melatonin. In addition, melatonin is an effective antioxidant which scavenges free radicals and up-regulates several antioxidant enzymes. It also has a strong antiapoptotic signaling function, an effect that it exerts even during ischemia. Melatonin cytoprotective properties may have practical implications in the treatment of ocular diseases, like glaucoma and age-related macular degeneration.