Case Report: Spectrum of interesting ocular manifestations following COVID-19 vaccination: a case series of real-world presentations.

Purpose: We report the ocular findings that patients experienced after receiving the coronavirus disease 2019 (COVID-19) vaccination in three different eye centers in Malaysia. Observations: A total of four cases were reported. Three patients received the Pfizer-BioNTech vaccine, while the other received the Oxford AstraZeneca type. Ocular symptoms occurred after the first vaccine dose in two patients and after the second vaccine dose in the other two. Three out of four patients required active treatment for their vision complications postvaccination. The first patient had acute-onset retinal pigment epitheliitis within 3 h of vaccination and was treated conservatively. The second patient developed unilateral choroidal neovascularization 3 days after vaccination and required intravitreal antivascular endothelial growth factor injection. The third patient presented with bilateral acute multifocal placoid pigment epitheliopathy a week after vaccination and responded to intravenous methylprednisolone. The fourth patient presented with herpes zoster infection and unilateral anterior nongranulomatous uveitis 2 weeks after vaccination and was treated with oral acyclovir and topical corticosteroids. All patients reported some amount of visual recovery. Conclusions and importance: Visual symptoms and various ocular adverse events can occur following COVID-19 vaccination, which warrants further investigation and urgent intervention if necessary. We would suggest patients receiving the COVID-19 vaccination be aware of possible ocular complications and report any symptoms, regardless of severity.

Oculomotor and trochlear nerve neuritis following botulinum toxin injection for masseter hypertrophy - a case report with literature review.

OBJECTIVE: To report a rare complication of oculomotor and trochlear nerve neuritis following botulinum toxin injection for masseter hypertrophy. CASE PRESENTATION: A previously healthy 31-year-old man presented with a two-week history of left eye (OS) ptosis and diplopia, following botulinum toxin injection over the masseter area for masseter hypertrophy at an aesthetic centre. He had no proptosis or facial asymmetry. Visual acuity was 6/6 in the right eye (OD) and 6/9 in the OS. There was anisocoria, with pupils measuring 3 mm in the OD and 5 mm in the OS but no relative afferent pupillary defect. OS appeared hypertropic in primary gaze with impaired intorsion. Extraocular movement of the OS was restricted in all gazes, except for laevoversion; that of the OD was normal. This was associated with diplopia in all gazes except on laevoversion. Both eyes' anterior and posterior segment examinations were otherwise unremarkable. Besides the oculomotor and trochlear nerve, the other cranial nerves and neurological examinations were normal. Investigations including blood and cerebrospinal fluid, magnetic resonance imaging and angiography of the brain, were normal. Our impression was left oculomotor and trochlear nerve neuritis secondary to botulinum toxin injection. He was started on oral prednisolone 1 mg/kg daily and tapered by 5 mg per week. His condition improved gradually with no residual ptosis or anisocoria after three months. Extraocular movements normalised except for minimal residual restriction on depression. CONCLUSION: Oculomotor and trochlear nerve neuritis can occur following botulinum toxin injection over the masseter area. Healthcare professionals should be aware of this potential complication before offering the injection.

Lights Off, Lights On: Amaurosis Fugax in Polycythemia.

There are many causes of amaurosis fugax, including polycythemia. Polycythemia is associated with elevated hematocrit levels and hyperviscosity, which can lead to ocular manifestations. We report a polycythemia patient with amaurosis fugax, who had resolution of ocular symptoms following venesection. A 29-year-old gentleman presented with a six-month history of episodic bilateral transient loss of vision (amaurosis fugax), followed by slow recovery back to normal after 15-20 minutes. The symptoms worsened with fatigue. He also had an unsteady gait for the preceding one year. Ocular examination was unremarkable. His visual acuity was 20/20 OU. Neurological examination revealed gait ataxia and dysdiadochokinesia. Computed tomography (CT) angiogram showed an old cerebellar infarct. Blood investigations showed persistent elevated hemoglobin and hematocrit with positive JAK-2 V617F mutation. Infective and connective tissue workups were all negative. A diagnosis of polycythemia was made by the haematology team. In addition to oral aspirin given by the neurology team, he underwent venesection with improvement in ocular symptoms following each episode of venesection. The frequency of amaurosis fugax reduced from 2-3 episodes a week to once a month, then resolved completely after five venesections. Systemically, his cerebellar symptoms also resolved and there were no neurological deficits. Polycythemia is a rare disease that can cause amaurosis fugax and thrombotic events in young patients. Better knowledge and accurate diagnosis are important, as early treatment may improve the symptoms and long-term morbidity.

Pasteurella Multocida Panophthalmitis: A Devastating Sequela of an Industrial Penetrating Injury.

Pasteurella multocida is a rare but aggressive causative organism in panophthalmitis. It is commonly transmitted to humans through contact with cats and dogs as a result of bites or scratches. We report a rare case of panophthalmitis due to P. multocida following an industrial penetrating injury. A previously healthy 40-year-old steel factory operator developed a right eye penetrating injury after being struck accidentally by a piece of iron wire which flew into his eye during work. He complained of immediate blurring of vision and severe pain in the affected eye. During history taking, he mentioned that many stray cats wandered around his workplace, although he had no direct contact with these animals. On examination, the best-corrected visual acuity was light perception in the right eye. Slit-lamp biomicroscopy revealed injected conjunctiva and a full-thickness macerated corneal laceration wound. The anterior chamber appeared shallow with the presence of lens matter. He was treated promptly with surgical repair along with intracameral and intravenous antibiotics for six hours post-trauma. His eye condition, however, deteriorated postoperatively despite aggressive treatment with further topical, intravitreal, and systemic antibiotics. This is the first reported case of ocular P. multocida panophthalmitis secondary to industrial penetrating injury. Our case highlights the rapidly progressive nature of P. multocida infection. It should always be considered due to the very serious nature of infection as well as its resistance to standard antibiotic treatment regimens.

COMPARISON OF SMARTPHONE-BASED AND AUTOMATED REFRACTION WITH SUBJECTIVE REFRACTION FOR SCREENING OF REFRACTIVE ERRORS.

PURPOSE: To compare Netra smartphone-based and automated refraction with subjective refraction for screening of refractive errors. METHODS: Cross-sectional study at the University of Malaya Medical Centre, Kuala Lumpur. Subjects underwent subjective refraction, then automated refraction, and finally Netra smartphone-based refraction. All results were converted to power vectors (M, J0 and J45) and were analysed using repeated-measures ANOVA and Bland-Altman plots. Sensitivity and specificity were determined. The best cut-off points were determined from ROC curve analysis. P < .05 was considered statistically significant. RESULTS: Data from the right eyes of 204 subjects were analysed. Mean age was 36.6 ± 15.7 years (range 16-78 years). Spherical equivalent [mean (95% CI)] from Netra and automated refraction were similar, and both more myopic than subjective refraction; -2.87 (-3.23 to -2.51), -2.85 (-3.21 to -2.49) and -2.46 (-2.83 to -2.10) respectively (p < .001). Differences in J0 and J45 between Netra and subjective refraction were not statistically significant (0.10 vs 0.11 and 0.01 vs -0.02 respectively, both p > .05), but those between automated and subjective refraction were (0.06 vs 0.11 and 0.07 vs -0.02, p = .004 and p < .001 respectively). Bland Altman plots showed the 95% limits of agreement with Netra refraction were wider than with automated refraction (-2.21D to 1.42D vs. -1.90D to 1.16D respectively). CONCLUSION: Netra smartphone-based refraction gives similar readings to automated refraction, and both show myopic overestimation when compared to subjective refraction. However, due to non-insignificant practical usage issues, its use as a screening tool for refractive errors is limited.

Encephalocraniocutaneous Lipomatosis: A Case Report and Literature Review.

Encephalocraniocutaneous lipomatosis (ECCL) or Haberland syndrome is a neurocutaneous disorder of the skin, eye, and central nervous system. A three-month-old girl was referred to our center for further management of a large left eye corneal dermoid. At birth, a small lesion was noted. Magnetic resonance imaging (MRI) around the first week of life showed an extraocular dermoid cyst measuring 1 mm x 7 mm, dysplasia of the left greater wing of sphenoid, closed-lip schizencephaly of the left parietal lobe, and polymicrogyria. During examination under anesthesia at our center, we found that the corneal dermoid had grown in size to 17 mm x 16 mm, with posterior embryotoxon, a hazy cornea, and intraocular pressure of 26 mmHg. With the anterior segment dysgenesis and secondary glaucoma, we started Gutt Timo-Comod BD. Serial MRI imaging at four months of age revealed further enlargement of the dermoid, a new left retrobulbar mass, and multiple intracranial lipomas. A diagnosis of ECCL was made at this point based on the MRI and clinical findings. A multidisciplinary meeting was held among ophthalmology, neurosurgery, radiology, and otorhinolaryngology (ORL) teams, which concluded that surgical intervention such as tumor debulking might cause more harm than benefit. Hence, she was planned to undergo close monitoring with serial MRIs and only for surgical intervention, in the presence of airway compression or any neurological deficits. The ophthalmologist should be aware of the specific radiological and clinical findings in ECCL as management of the condition would be best through a multidisciplinary approach.

The Noxious Intruder of the Eye: Endogenous Klebsiella Panophthalmitis.

Endogenous Klebsiella pneumoniae panophthalmitis commonly affects those with compromised immunity. The occurrence of this infection in healthy individuals is rare. We describe the case of a healthy adult who presented with endogenous Klebsiella pneumoniae panophthalmitis from an asymptomatic liver abscess. A 64-year-old, previously healthy gentleman presented with rapidly progressive left eye periorbital swelling and blurring of vision. He had a low-grade fever three days prior to the development of ocular symptoms, but otherwise no other systemic complaints. Visual acuity was light perception in the left eye, and ocular motility was restricted in all directions of gaze. Ocular examination revealed proptosis, severe conjunctival chemosis, hazy cornea, and fibrin deposition in the anterior chamber. The posterior segment could not be visualized. Ultrasound of the hepatobiliary system revealed an abscess in the right lobe of his liver. His blood cultures grew Klebsiella pneumoniae. Despite being treated with high-dose intravenous antibiotics, his eye condition deteriorated. Evisceration was performed when he developed scleral melting and globe perforation. We highlight the importance of a high index of suspicion of endogenous Klebsiella panophthalmitis as it can be easily missed in healthy adults. Early diagnosis and prompt management are needed to prevent morbidity and mortality from this devastating infection.

Effectiveness of simple interventions to remind eye doctors to educate glaucoma patients about the dangers of driving.

PURPOSE: A clinical audit to establish whether eye doctors achieve the benchmark in reminding glaucoma patients about the dangers of driving. After introducing two simple interventions, a follow-up audit was performed. METHODOLOGY: Initially, we interviewed 85 patients with established glaucoma who underwent Humphrey visual field (HVF) testing and also reviewed their medical notes. We looked for documentation of their driving status, specifically whether those with bilateral visual field (VF) defects recalled being given advice about the dangers of driving and whether this was documented in the notes. After this initial audit, doctors were educated on the availability of guidelines on visual requirements for driving, and reminder adhesive labels were put on the front of medical notes of driving glaucoma patients. A follow-up audit was then performed on 95 different patients. RESULTS: In the initial audit, none of the patients had their driving status recorded. Only 36% of drivers with bilateral VF defects recalled being advised of the dangers of driving, with no documentation of whether the advice was given to them. Following the interventions, documentation of driving status became 86%. All drivers with bilateral VF defects recalled being advised regarding the dangers of driving, with documentation of the advice being given recorded in 73% of the medical notes. CONCLUSION: Eye doctors are inadequately identifying, advising, and documenting the dangers of driving in the medical notes of glaucoma patients with bilateral VF defects. This can be improved with simple interventions, such as the education of doctors and creating reminder labels, for the benefit of our glaucoma patients.

Cytomegalovirus retinitis associated with high CD4 counts and DHEA abuse.

The most frequent ocular manifestation of acquired immunodeficiency syndrome (AIDS) is cytomegalovirus retinitis (CMVR). This infection is reportedly inversely proportional to the CD4 counts. Usually CMVR develops once the CD4 counts fall below 50/mm3. Our case report documents an AIDS patient who developed CMVR despite CD4 counts being persistently >200/mm3. The patient was self-administering dehydroepiandrosterone, high dose Vitamin C, testosterone and hydrocortisone. This case report describes a unique case of pharmacologically induced elevated CD4 counts, which however, did not prevent the development of CMVR in the patient.

Subfoveal Choroidal Thickness in Pre-eclampsia.

SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between subfoveal choroidal thickness (SFCT) and the parameters affecting the severity of pre-eclampsia has been reported. We provide evidence that SFCT is thicker in pre-eclamptic (PE) patients and speculate on the possible causes. PURPOSE: The purposes of this study were to compare SFCT in PE, normal pregnant, and nonpregnant women using spectral domain optical coherence tomography and to correlate SFCT with severity of pre-eclampsia. METHODS: A cross-sectional, observational study was performed. A total of 150 participants were divided into three groups: group 1 (50 PE women), group 2 (50 normal pregnant women), and group 3 (50 nonpregnant healthy women). Subfoveal choroidal thickness was measured using spectral domain optical coherence tomography. Other parameters including mean arterial blood pressure (MABP), central corneal thickness, macular thickness, IOP, ocular perfusion pressure (OPP), and urine protein-to-creatinine ratio were also measured. ANOVA and Pearson correlation analysis were used to look at differences between the groups. P < .05 was considered as statistically significant. RESULTS: The MABP was higher in group 1 than in groups 2 and 3 (103.0 ± 12.9 vs. 83.2 ± 9.8 vs. 89.5 ± 7.2 mmHg, respectively; all P < .001). The SFCT of the PE group was higher than in groups 2 and 3 (370.7 ± 23.8 vs. 344.5 ± 30.8 vs. 315.8 ± 49.9 µm, respectively; all P < .001). There were no statistically significant differences in central corneal thickness, macular thickness, or IOP between the PE and healthy pregnant groups (all P > .05). The OPP was greater in PE patients (52.8 ± 8.5 vs. 41.9 ± 6.9 vs. 43.4 ± 5.2 mmHg, respectively; both P < .001). The SFCT was positively correlated with MABP (r = 0.464, P < .001), OPP (r = 0.495, P < .001), and urine protein-to-creatinine ratio (r = 0.635, P < .001) in the PE group. CONCLUSIONS: Subfoveal choroidal thickness is higher in pre-eclampsia and is proportional to established markers of severity of the condition. This parameter might serve as a novel predictive marker for the severity of pre-eclampsia.

Unilateral ischaemic retinopathy and bilateral subdural haemorrhage in an infant with non-accidental injury: An ophthalmological approach.

Non-accidental injury (NAI) is not an uncommon problem worldwide, which leads to significant morbidity and mortality in infants. The presence of retinal or subdural haemorrhages, or encephalopathy with injuries inconsistent with the clinical history is highly suggestive of NAI. In this study, we report on a case of a a 3-month-old infant who presented to the casualty department with a very sudden onset of recurrent generalised tonic-clonic seizures. There was no history of trauma or visible external signs. She was found to have bilateral subdural haemorrhages and atypical unilateral ischaemic retinopathy. Retinal photocoagulation was performed with subsequent resolution of vitreous and retinal haemorrhages. However, visual recovery in that eye remained poor. The findings showed that a high index of suspicion of NAI is required in infants with intracranial haemorrhage and unilateral retinal haemorrhages.

Choroidal thickness in Malaysian eyes with full-thickness macular holes / 国际眼科杂志(Guoji Yanke Zazhi)

·AIM: To compare choroidal thickness at the macula in eyes with unilateral idiopathic full - thickness macular holes (FTMH) with that of unaffected fellow eyes, and eyes of normal control patients. ·METHODS: Cross-sectional study. Thirty patients with unilateral idiopathic FTMH and thirty age, sex, and race-matched controls were recruited. Axial lengths were measured using laser interferometry. Enhanced depth imaging optical coherence tomography images were obtained using Heidelberg spectral - domain optical coherence tomography. Choroidal thickness was measured at the fovea, and at 1 mm and 2 mm nasally, temporally, superiorly and inferiorly from the center of the fovea. Statistical analysis was performed using independent and paired t-tests, chi-square tests, and Pearson correlation tests (P<0.05). ·RESULTS:The mean subfoveal choroidal thickness was 201.0±44.0 μ m in the FTMH group,225.3± 51.4 μ m in the fellow eye group and 262.3±70.3 μ m in the control group. The choroid was thinner in FTMH eyes at all locations when compared to control eyes(P<0.05). The fellow eye group also had thinner choroids than the control group at all locations except at 1 mm and 2 mm nasal to the fovea (P<0.05). Choroidal thickness in the FTMH group was lower than in the fellow eye group, but the differences were not statistically significant (P > 0.05). Choroidal thickness was generally highest subfoveally and lowest nasally. Subfoveal choroidal thickness was negatively correlated with age (r = -0.278, P = 0.032), and axial length (r=-0.328,P=0.011). ·CONCLUSION:Choroidal thickness is lower in both eyes of patients with unilateral FTMH compared to healthy control eyes.

Corneal Hysteresis Is Reduced in Obstructive Sleep Apnea Syndrome.

SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between corneal hysteresis (CH) and obstructive sleep apnea syndrome (OSAS) severity has been reported. We provide evidence that CH is lower in OSAS and speculate on the possible causes. PURPOSE: The present study aims to look at the association between CH and severity of OSAS, and whether CH could be another link between OSAS and the development of glaucoma. METHODS: This was a cross-sectional, observational study at the University Malaya Medical Centre, Kuala Lumpur. Patients undergoing polysomnography for assessment of OSAS were recruited. We measured central corneal thickness (CCT) using optical biometry, and CH using ocular response analysis. Intraocular pressure (IOP) and Humphrey visual field (HVF) indices were also measured. The Apnea Hypopnea Index (AHI) divided patients into normal, mild, moderate, and severe OSAS categories. The normal and mild categories (47.9%) were then collectively called group 1, and the moderate and severe categories (52.1%) were called group 2. T tests, Pearson correlation tests, and general linear model analysis were performed, with P <.05 considered statistically significant. RESULTS: One eye each from 117 patients (75 men, 42 women) was included. Patients in group 2 had lower CH (9.8 ± 1.4 vs. 10.3 ± 1.1 mm Hg, P = .029), with unchanged estimated marginal means after correcting for age, sex, CCT, and IOP (P = .026). There were no statistically significant differences in IOP, CCT, or HVF indices between the two groups (all P > .05). CH correlated negatively with AHI (r = -0.229, P = .013) and positively with lowest oxygen saturation (r = 0.213, P = .022). CONCLUSIONS: CH is lower in moderate/severe OSAS than in normal/mild cases. This may be another link between OSAS and the development of glaucoma; further studies are indicated to determine the significance of this connection.

Effect of Nocturnal Intermittent Peritoneal Dialysis on Intraocular Pressure and Anterior Segment Optical Coherence Tomography Parameters.

PURPOSE: To evaluate the effect of nocturnal intermittent peritoneal dialysis (NIPD) on intraocular pressure (IOP) and anterior segment optical coherence tomography (ASOCT) parameters. Systemic changes associated with NIPD were also analyzed. METHODS: Observational study. Nonglaucomatous patients on NIPD underwent systemic and ocular assessment including mean arterial pressure (MAP), body weight, serum osmolarity, visual acuity, IOP measurement, and ASOCT within 2 hours both before and after NIPD. The Zhongshan Angle Assessment Program (ZAAP) was used to measure ASOCT parameters including anterior chamber depth, anterior chamber width, anterior chamber area, anterior chamber volume, lens vault, angle opening distance, trabecular-iris space area, and angle recess area. T tests and Pearson correlation tests were performed with P<0.05 considered statistically significant. RESULTS: A total of 46 eyes from 46 patients were included in the analysis. There were statistically significant reductions in IOP (-1.8±0.6 mm Hg, P=0.003), MAP (-11.9±3.1 mm Hg, P<0.001), body weight (-0.7±2.8 kg, P<0.001), and serum osmolarity (-3.4±2.0 mOsm/L, P=0.002) after NIPD. All the ASOCT parameters did not have any statistically significant changes after NIPD. There were no statistically significant correlations between the changes in IOP, MAP, body weight, and serum osmolarity (all P>0.05). CONCLUSIONS: NIPD results in reductions in IOP, MAP, body weight, and serum osmolarity in nonglaucomatous patients.

Ocular perfusion pressure and ophthalmic artery flow in patients with normal tension glaucoma.

BACKGROUND: Vascular insufficiency has been reported to be a cause of normal tension glaucoma (NTG). The aim of this study was to compare ocular perfusion pressure (OPP) and ophthalmic artery flow (OAF) between patients with NTG and those without glaucoma. METHODS: We considered one eye each from 31 NTG and 15 non-glaucoma control patients. Blood pressure and intraocular pressure (IOP) were measured in the sitting position, for calculation of OPP. Humphrey visual field (HVF) assessment was then carried out on NTG patients. All patients then underwent Transcranial Doppler ultrasound measurements of OAF parameters, including mean flow velocity (MFV), end diastolic velocity (EDV), peak systolic velocity (PSV) and resistive index (RI). We looked at differences in OPP and OAF parameters between the two groups, and their correlations in NTG patients. T-tests, χ (2), ANOVA and Pearson Correlation tests were performed, with p < 0.05 considered statistically significant. RESULTS: There were no statistically significant differences in OPP between the NTG and control groups (60.5+/-8.7 mmHg and 62.9+/-10.2 mmHg respectively, p = 0.393), and also no statistically significant differences in MFV, EDV, PSV and RI (all p > 0.05). In the NTG group, there were positive correlations between OPP and both MFV (r = 0.416, p = 0.020) and EDV (r = 0.369, p = 0.041). There were no statistically significant correlations between HVF mean deviation and OPP or OAF parameters (all p > 0.05). CONCLUSION: There is no difference in OPP and OAF parameters between patients with NTG and non-glaucoma controls, suggesting that vascular insufficiency or dysregulation by themselves may not account for the pathogenesis of NTG.

Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes.

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

The Influence of Scleral Flap Thickness, Shape, and Sutures on Intraocular Pressure (IOP) and Aqueous Humor Flow Direction in a Trabeculectomy Model.

PURPOSE: Intraocular pressure and aqueous humor flow direction determined by the scleral flap immediately after trabeculectomy are critical determinants of the surgical outcome. We used a large-scale model to objectively measure the influence of flap thickness and shape, and suture number and position on pressure difference across the flap and flow of fluid underneath it. METHODS: The model exploits the principle of dynamic and geometric similarity, so while dimensions were up to 30× greater than actual, the flow had similar properties. Scleral flaps were represented by transparent 0.8- and 1.6-mm-thick silicone sheets on an acrylic plate. Dyed 98% glycerin, representing the aqueous humor was pumped between the sheet and plate, and the equilibrium pressure measured with a pressure transducer. Image analysis based on the principle of dye dilution was performed using MATLAB software. RESULTS: The pressure drop across the flap was larger with thinner flaps, due to reduced rigidity and resistance. Doubling the surface area of flaps and reducing the number of sutures from 5 to 3 or 2 also resulted in larger pressure drops. Flow direction was affected mainly by suture number and position, it was less toward the sutures and more toward the nearest free edge of the flap. Posterior flow of aqueous humor was promoted by placing sutures along the sides while leaving the posterior edge free. CONCLUSION: We demonstrate a new physical model which shows how changes in scleral flap thickness and shape, and suture number and position affect pressure and flow in a trabeculectomy.

Evaluation of Dimensional and Flow Properties of ExPress Glaucoma Drainage Devices.

PURPOSE: ExPress devices are available as P50 and P200 models, the numbers related to their luminal diameters in µm. We compared their Poiseuille's Law-based theoretical resistance values with experimental values and correlated these with their luminal dimensions derived from electron microscopy. METHODS: Scanning electron microscopy was performed on P50 and P200 devices. Bench-top flow studies were performed to find the resistances of the devices. Devices were also incorporated into a perfused, ex vivo porcine sclera model to test and compare their control of pressure, with and without overlying scleral flaps, and with trabeculectomies. RESULTS: The luminal dimensions of the P200 device were 206.4±3.3 and 204.5±0.9 µm at the subconjunctival space and anterior chamber ends, respectively. Those of the P50 device were 205.0±5.8 and 206.9±3.7 µm, respectively. There were no significant differences between the P200 and P50 devices (all P>0.05). The resistances of the P200 and P50 devices were 0.010±0.001 and 0.054±0.002 mm Hg/µL/min, respectively (P<0.05). Equilibrium pressures with overlying scleral flaps were 17.81±3.30 mm Hg for the P50, 17.31±4.24 mm Hg for the P200, and 16.28±6.67 mm Hg for trabeculectomies (P=0.850). CONCLUSIONS: The luminal diameters of both devices are externally similar. The effective luminal diameter of the P50 is much larger than 50 µm. Both devices have low resistance values, making them unlikely to prevent hypotony on their own. They lead to similar equilibrium pressures as the trabeculectomy procedure when inserted under the scleral flap.

Proptosis--Correlation and Agreement between Hertel Exophthalmometry and Computed Tomography.

AIM: To determine the correlation and agreement between Hertel exophthalmometry and computed tomography (CT) of the orbits in measuring proptosis. MATERIALS AND METHODS: 80 patients (40 normal and 40 with proptosis) were recruited for this study. Exophthalmometry were performed on all of them using the Hertel exophthalmometer and CT. Values and correlations between the modalities were analysed with unpaired t-tests, intraclass correlation coefficients (ICC), and Pearson correlation coefficients (PCC). The Bland-Altman method was used to analyse the agreement between the two modalities. RESULTS: Hertel exophthalmometer and CT measurements did not differ significantly (p > 0.05), although exophthalmometry measurements of the normal (14.5 ± 2.2 mm) and proptosis groups (20.5 ± 3.9 mm) were higher than those obtained from CT (13.9 ± 2.4 mm and 20.0 ± 3.7 mm, respectively). ICC for both the Hertel exophthalmometer and CT measurements were both 0.99, indicating high intra-observer reliability and reproducibility. PCC between Hertel exophthalmometer and CT measurements in both normal and proptosis groups were strongly correlated (r = 0.96 and 0.93, respectively, p = 0.01). The 95% limits of agreement (LOA) between Hertel exophthalmometer and CT measurements for the normal and proptosis groups were -0.70 to 1.78 mm and -2.36 to 3.33 mm, respectively. CONCLUSION: Although Hertel exophthalmometer and CT measurements are similar and strongly correlated, they do not agree well with each other in the presence of proptosis. The measurements should not be used interchangeably as the differences between them may lead to errors in clinical interpretation.

Ocular Surface Disease in Glaucoma: Effect of Polypharmacy and Preservatives.

PURPOSE: To evaluate the prevalence of ocular surface disease (OSD) in glaucoma and nonglaucoma subjects using different clinical tests and to determine the effect of number of antiglaucoma medications and preservatives on OSD. METHODS: This is a cross-sectional, case-comparison study at the Eye Clinic of the University of Malaya Medical Centre, Malaysia, between June 2012 and January 2013. Glaucoma subjects (n = 105) using topical antiglaucoma medications were compared with control subjects (n = 102) who were not on any topical medications. The presence of OSD was assessed using the tear film breakup time (TBUT) test, corneal staining, Schirmer test, and Ocular Surface Disease Index (OSDI) questionnaire grading. RESULTS: The prevalence of OSD varied from 37 to 91% in the glaucoma group, depending on the type of clinical test. More subjects in the glaucoma group had corneal staining (63% vs. 36%, p = 0.004), abnormal Schirmer tests (39% vs. 25%, p = 0.049), and moderate OSDI symptoms (17% vs. 7%, p = 0.028). The percentage with abnormal TBUT increased with higher numbers of topical medications and was high with both benzalkonium chloride-containing and preservative-free eye drops (90% and 94%, respectively, both p < 0.001). Benzalkonium chloride was associated with a nearly three times higher odds ratio of showing abnormal OSDI. CONCLUSIONS: Ocular surface disease is common in those using topical antiglaucoma medications. Abnormal TBUT is associated with increasing number of eye drops and benzalkonium chloride-containing eye drops, although this also occurs with the use of preservative-free eye drops.