Acetylcholinesterase (AChE) is an important link in the apoptotic pathway induced by hyperglycemia in Y79 retinoblastoma cell line.

Acetylcholinesterase (AChE) expression was found to be induced in the mammalian CNS, including the retina, by different types of stress leading to cellular apoptosis. Here, we tested possible involvement of AChE in hyperglycemia-induced apoptosis in a retinal cell line. Y79 retinoblastoma cells were incubated in starvation media (1% FBS and 1 mg/ml glucose) for 16-24 h, and then exposed to hyperglycemic environment by raising extracellular glucose concentrations to a final level of 3.5 mg/ml or 6 mg/ml. Similar levels of mannitol were used as control for hyperosmolarity. Cells were harvested at different time intervals for analysis of apoptosis and AChE protein expression. Apoptosis was detected by the cleavage of Poly ADP-ribose polymerase (PARP) using western blot, and by Terminal deoxynucleotidyl-transferase-mediated dUTP nick-end-labeling (TUNEL) assay. AChE protein expression and activity was detected by western blot and by the Karnovsky and Roots method, respectively. Mission(TM) shRNA for AChE was used to inhibit AChE protein expression. Treating Y79 cells with 3.5 mg/ml of glucose, but not with 3.5 mg/ml mannitol, induced apoptosis which was confirmed by TUNEL assay and by cleavage of PARP. A part of the signaling pathway accompanying the apoptotic process involved up-regulation of the AChE-R variant and an N-extended AChE variant as verified at the mRNA and protein level. Inhibition of AChE protein expression by shRNA protected Y79 cell from entering the apoptotic pathway. Our data suggest that expression of an N-extended AChE variant, most probably an R isoform, is involved in the apoptotic pathway caused by hyperglycemia in Y79 cells.

Orthokeratology associated microbial keratitis.

PURPOSE: To report the clinical course, microbiologic findings, treatment, and outcomes of overnight orthokeratology associated microbial keratitis. METHODS: Four cases of overnight orthokeratology associated microbial keratitis are reported. RESULTS: Four patients aged 14-23 years (mean 18 years) who had central or paracentral corneal ulcers were included. Visual acuity at presentation ranged from 20/30 to hand motion. In all cases Pseudomonas aeruginosa was cultured from corneal scrapings or storage solution. In all patients the infection resolved with intensive topical antimicrobial treatment. Final best-corrected visual acuity ranged from 20/25 to 20/200 according to the location, size, and density of the corneal scar, which complicated all cases. CONCLUSIONS: Infectious keratitis is a significant, visual threatening complication of overnight orthokeratology. Eye care practitioners should be aware of this complication and educate their patients of the importance of lens hygiene and prompt medical care when symptoms or signs of keratitis appear.

The response of retrobulbar vasculature to hypercapnia in primary open-angle glaucoma and ocular hypertension.

PURPOSE: To evaluate the physiological effects of hypercapnia on the retrobulbar vasculature in ocular hypertension (OH) and open-angle glaucoma (OAG). METHODS: Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) of the ophthalmic (OA) and central retinal arteries (CRA) were evaluated in 12 eyes with OH and 8 eyes with OAG using color Doppler imaging. Measurements were taken before and during hypercapnia. RESULTS: Patients with OAG were found to have increased EDV (p < 0.035) of the CRA, and decreased PSV (p < 0.097) and EDV (p < 0.098) of the OA, during hypercapnia. Patients with OH had increased PSV (p < 0.062) and EDV (p < 0.072) of the CRA during hypercapnia. Patients with OH also demonstrated a greater percent change in the calculated RI (p < 0.065) of the CRA in response to hypercapnia when compared to OAG. The mean RI of the CRA decreased during hypercapnia. DISCUSSION: Patients with OH were found to have a normal vasodilatory response within the retrobulbar vasculature during hypercapnia resulting in increased volumetric blood flow to the retina while patients with OAG did not, suggesting there is vasospasm at or downstream from the CRA resulting in decreased volumetric blood flow to the retina.

Ocular haemodynamic responses to induced hypercapnia and hyperoxia in glaucoma.

AIM: To determine the ocular haemodynamic response to gas perturbations in glaucoma. METHODS: Intraocular pressure (IOP), systemic systolic and diastolic blood pressure (SBP and DBP), and retrobulbar blood flow velocities, measured by colour Doppler imaging (CDI), were recorded at two visits. CDI was used to measure peak systolic and end diastolic velocities (PSV and EDV) and resistance index (RI) in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs). At the first visit, measurements were taken at baseline (B1: breathing room air) and during isoxic hypercapnia (end tidal PCO(2) increased 15% above baseline) in 16 normal subjects and 12 patients with glaucoma. On another day, measurements were repeated at a second baseline (B2) and during hyperoxia (100% oxygen breathing) for 15 normal subjects and 13 glaucoma patients. Baseline systemic data were compared using paired t tests; REANOVA was performed to compare group differences at baseline and to determine the vessel response to each condition. Fisher's LSD was used for post hoc comparison. RESULTS: Baseline OA PSV was lower for the glaucoma than for the normal group (p = 0.047); the groups were otherwise similar at baseline. IOP demonstrated no response to hypercapnia, but reduced during hyperoxia for both the normal subjects (p<0.0001) and glaucoma patients (p = 0.04). During hypercapnia, SBP increased in normal subjects (p = 0.03) and glaucoma patients (p = 0.01); DBP increased in normal subjects (p = 0.021). There was a corresponding increase in ocular perfusion pressure (OPP) for normal subjects (p = 0.01) and glaucoma subjects (p = 0.028), and as a result OPP was included as a covariate in the REANCOVA model. Hypercapnia resulted in increased PSV in the CRA of normal subjects (p = 0.035) and increased PSV and EDV in the SPCAs of glaucoma patients (p = 0.041 and p = 0.030 respectively). Hyperoxia resulted in reduced PSV and EDV in the ophthalmic arteries of normal subjects only (p = 0.001 and 0.031 respectively). CONCLUSIONS: These findings suggest the presence of relative vasoconstriction in glaucoma patients, which is at least partially reversed by hypercapnia.

The effects of dorzolamide on choroidal and retinal perfusion in non-exudative age related macular degeneration.

AIM: To comprehensively evaluate the effects of dorzolamide on the choroidal and retinal circulation in patients with age related macular degeneration (AMD). METHODS: In this randomised, double masked, parallel study, 36 non-exudative AMD patients were randomised in a 2 to 1 fashion to placebo versus topical dorzolamide and underwent assessment of their choroidal and retinal circulation. Scanning laser ophthalmoscope indocyanine green angiograms (ICGA) were analysed by a new area dilution analysis technique. Four areas in the perifoveal region and two areas in the temporal peripapillary region were evaluated by plotting intensity of fluorescence of each area over time. The means of the choroidal filling times and the heterogeneity of the filling times were assessed. Scanning laser ophthalmoscope fluorescein angiography (FA) was evaluated for retinal arteriovenous passage (AVP) times by plotting intensity of fluorescence of retinal vessels over time. Assessment was performed at baseline and at 4 months. RESULTS: Compared to placebo, AMD patients treated with dorzolamide showed a significantly increased rapidity of choroidal filling in the superior and inferior peripapillary regions (p=0.007, p=0.02, respectively). No significant difference in choroidal filling times was found in any of the perifoveal areas (p=0.9). Also, on FA assessment, treatment with dorzolamide showed no statistical differences in AVP times (p=0.19). CONCLUSIONS: Dorzolamide may increase peripapillary choroidal perfusion in non-exudative AMD patients. Further studies are merited.

Comparative analysis of the effects of dorzolamide and latanoprost on ocular hemodynamics in normal tension glaucoma patients.

PURPOSE: To compare the effects of latanoprost (Xalatan) and dorzolamide (Trusopt) on ocular hemodynamics in normal-tension glaucoma patients. METHODS: A randomized, single-masked, parallel design study was conducted. After a 4-week washout period, 20 normal tension glaucoma patients, recruited from a single university-based ophthalmology clinic, received either latanoprost once daily or dorzolamide 3 times daily for 4 weeks. The subjects were examined at baseline and post-treatment. Outcome measures included heart rate (HR), blood pressure (BP), logMar visual acuity (VA), contrast sensitivity (CS), intraocular pressure (IOP), color Doppler imaging (CDI), and fluorescein angiography with the Rodenstock scanning laser ophthalmoscope (SLO). CDI measurements of the retrobulbar vessels included peak systolic velocity, end diastolic velocity, and the calculated resistance index. Arterio-venous passage time (AVP) in the superior and inferior temporal retina was calculated from the SLO angiograms. RESULTS: Neither dorzolamide nor latanoprost had any statistically significantly effect on HR or BP. Both drugs significantly lowered IOP without altering calculated ocular perfusion pressure (p<0.05). There was no statistically significant difference in any CDI measurement. Dorzolamide significantly decreased AVP time in the superior retina (p=0.011), while latanoprost did not (p=0.62). CONCLUSIONS: Dorzolamide, unlike latanoprost, significantly reduced AVP times in the superior temporal retina in normal tension glaucoma (NTG) patients.

Blood flow per unit retinal nerve fibre tissue volume is lower in the human inferior retina.

AIM: To determine if perfusion per unit tissue volume of retinal nerve fibre layer and optic nerve head in the inferior sector is lower than in the superior sector. METHODS: Heidelberg retinal tomogram (HRT) for topographic measurement of optic nerve head and retinal nerve fibre layer and Heidelberg retinal flowmeter (HRF) for retinal blood flow were performed on 19 normal healthy subjects. Measurements from the superior and inferior sectors were compared. The perfusion/nerve fibre ratio (PNR); the blood flow per unit retinal nerve fibre tissue volume, was calculated in each sector with a formula; HRF flow measurements divided by HRT measurements. RESULTS: Retinal nerve fibre layer thickness in the inferior retina was significantly higher than in the superior retina (p<0.05). There were, however, no differences in retinal blood flow between the superior and inferior retinal sectors. The PNR in the inferior sector were significantly lower than in the superior sector (p=0.047 for HRF mean flow/rim volume and p = 0.0282 for HRF 75th percentile flow/rim volume). CONCLUSIONS: The inferior sector of retinal nerve fibre layer and optic nerve head may have lower blood flow per unit nerve tissue volume compared to the superior sector. This result suggests that the inferior sector is more vulnerable to elevated intraocular pressure (IOP) and ischaemic insults in glaucomatous optic neuropathy.

Effect of intravenous droperidol on intraocular pressure and retrobulbar hemodynamics.

PURPOSE: Topically-applied dopamine antagonists reduce intraocular pressure (IOP) and inrease retinal blood flow in animal models. We examined the acute effects of intravenous infusion of a dopamine blocker (droperidol) on these parameters in healthy humans. METHODS: Sixteen subjects free from ocular or systemic disease (mean age 33 +/- 10 yrs) received either 5 mg i.v. droperidol over 5 minutes, or i.v. saline placebo in double-masked fashion. IOP was determined 30 and 60 minutes later, while color Doppler imaging was used to determine flow velocities in the ophthalmic, central retinal, and nasal and temporal posterior ciliary arteries 60 minutes after drug infusion. RESULTS: 30 minutes after drug infusion, IOP was reduced 6.0 mmHg as compared with baseline (p<0.001); after 60 minutes, IOP remained reduced by 3.7 mmHg (p<0.001). Placebo had no effect on IOP. While droperidol slightly elevated blood pressure and increased the calculated ocular perfusion pressure, the drug reduced visual acuity and contrast sensitivity (p<0.05). Droperidol elevated peak systolic velocity in the central retinal and nasal posterior ciliary arteries, without changing end-diastolic velocity or the resistance index in either of these vessels. Droperidol had no effect on flow velocities in the ophthalmic artery or the temporal posterior ciliary artery. CONCLUSIONS: The rapid and marked ocular hypotension resulting from intravenous droperidol suggests that this agent may prove useful in the management of acute ocular hypertension. The retrobulbar changes consequent to the ocular tension reduction likely represent autoregulatory responses to altered ocular perfusion pressure.

Effect of dorzolamide timolol combination versus timolol 0.5% on ocular bloodflow in patients with primary open-angle glaucoma.

PURPOSE: Addition of dorzolamide to timolol in primary open-angle glaucoma shows augmented reduction of intraocular pressure. It is unknown as yet if addition of dorzolamide will alter hemodynamics. METHODS: Fifteen patients with primary open-angle glaucoma were placed on a medication-dependent 1-week to 4-week washout that included maintenance on timolol. After washout, baseline measurements were taken (timolol). They were studied after a month on timolol or dorzolamide-timolol (Cosopt; Merck, Inc, Whitehouse Station, New Jersey), with the second drug preceded by another month of timolol maintenance and second baseline measurements. At each visit, visual function, intraocular pressure, and ocular hemodynamics were monitored, including indocyanine green and fluorescein angiography and color Doppler imaging. RESULTS: Cosopt significantly reduced intraocular pressure (14.7 to 13.4 mm Hg, P <.05) and increased arteriovenous passage time (superior temporal artery) of fluorescein dye (2.13 to 1.76 seconds, P =.01) but had no effect on visual function. CONCLUSIONS: When compared with timolol in primary open-angle glaucoma, Cosopt augments ocular tension reduction and reduces the amount of time required for blood to pass through the superior retinal vasculature.

A gene causing autosomal recessive cataract maps to the short arm of chromosome 3.

BACKGROUND: Fourteen loci have been associated with autosomal dominant cataract, but only one with the recessive form of the disease. OBJECTIVES: To find the chromosomal location of a gene causing autosomal recessive cataract in three inbred Arab families. METHODS: A single nucleotide polymorphism-based genome-wide search, with the Effvmetrix GeneChip HuSNP genotyping array, was performed on a pooled DNA sample from six affected family members in a search for regions showing homozygosity. Using conventional microsatellite markers, regions of homozygosity were further analyzed in all the families. RESULTS: A region on chromosome 3p spanning 43 megabases showed homozygosity with 13 consecutive SNPs. Three microsatellite markers from this region yielded lod scores > 3.00. A maximal two-point lod of 4.83 was obtained with the marker D3S1298 at theta = 0.004. Haplotype analysis placed the disease gene in a 20 Mb interval between D3S1768 and D3S2409. CONCLUSIONS: A gene causing autosomal recessive cataract maps to the short arm of chromosome 3.

Simultaneous management of blood flow and IOP in glaucoma.

Factors other than intraocular pressure (IOP) elevation must be involved in initiation and progression of glaucoma. An additional element in disease causation may be ischemia in the retina and optic nerve head. Ischemic damage to neurons in the CNS is similar mechanistically and histopathologically to changes seen in glaucoma. Further, glaucoma patients with normal IOP show clear evidence for cerebral and ocular ischemia. Aging and atherosclerosis reduce the ability of the eye to autoregulate blood flow when ocular perfusion pressure changes: the dependence of blood flow on perfusion pressure links ischemia to IOP. Consequently, neuroprotective treatments for glaucoma should be designed to both reduce IOP and improve ocular nutrient delivery.

Ocular blood flow measurements and their importance in glaucoma and age-related macular degeneration.

This survey of methods for assessing ocular hemodynamics in glaucoma and age-related macular degeneration is not complete, but it does cover those likely to be encountered in the literature. A fundamental problem in getting to grips with the ocular blood flow literature is the difficulty in comparing the results of similar studies employing different assessment techniques. As evident from the discussion above, each technique evaluates a portion of the ocular circulation in a distinct way. Some of the methods overlap with regard to the tissues that can be used for examination, while others are directed at entirely different parts of the ocular vasculature. Despite these difficulties, hemodynamic studies of glaucoma and AMD are likely to grow in importance. On the basis of accumulating epidemiological and clinical evidence, it is becoming apparent that intraocular pressure is not the sole etiological factor in glaucoma, and retinal pigment epithelium senescence is not the sole etiological factor in AMD. Circumstantial evidence of vascular involvement in glaucoma and AMD has now been bolstered by experimental evidence. If the current pace of refinement of newly established technologies for evaluating ocular blood flow is maintained, they will soon be ready for deployment in the clinic. The only problem is the availability of expensive instruments and trained personnel. The ultimate beneficiaries of work in this area will not be researchers, but patients.

Vitrectomy to remove a posteriorly dislocated endocapsular tension ring.

We treated a patient who had a posteriorly dislocated endocapsular ring associated with decreased vision and intravitreal cortical remnants. The ring was removed by uneventful pars plana vitrectomy. By the last examination, best corrected visual acuity had improved to 6/12 and intraocular pressure had stabilized to within normal limits. A posteriorly dislocated endocapsular ring is a rare complication of cataract surgery. Its removal by pars plana vitrectomy under direct observation is effective and safe.

Intraocular pressure and photorefractive keratectomy: a comparison of three different tonometers.

PURPOSE: To evaluate the intraocular pressure (IOP) with three different instruments, Goldmann applanation tonometer (GAT), noncontact tonometer, and Tono-Pen after photorefractive keratectomy (PRK) for myopia. METHODS: A prospective case series study to evaluate preoperative and postoperative IOP measurements of 149 eyes at 12 months. We performed GAT, noncontact tonometry, Tono-Pen central, and Tono-Pen temporal periphery measurements. We also performed measurements of the central corneal thickness (CCT) by ultrasonic pachymetry and keratometry. Pre-operative IOP reading served as control for all studies. RESULTS: After PRK, IOP reading was significantly reduced in the treated eyes when compared with the control measurements (11.87+/-1.73 vs. 13.37+/-1.52 mm Hg, p<0.0001 with GAT; 12.07+/-1.6 vs. 13.51+/-1.59 mm Hg, p<0.0001 with noncontact tonometer; 12.18+/-1.6 vs. 13.48+/-1.55 mm Hg, p<0.0001 with Tono-Pen central; 13.48+/-1.65 vs. 13.71+/-1.56 Hg, p<0.0104 with Tono-Pen temporal periphery). There was also a significant correlation between IOP reading changes measured by GAT, noncontact tonometer, Tono-Pen central, and change of CCT and between reduction of IOP reading and keratometry (r2>0.39, p<0.0001 for each). The correlation between IOP reading change by Tono-Pen temporal periphery and CCT was also significant but r2 value was only 0.034. Tono-Pen temporal periphery postoperative IOP measurements had the best correlation with preoperative GAT IOP (r2 = 0.57, p<0.0001). CONCLUSIONS: PRK reduced IOP reading as measured by GAT, noncontact tonometer, and Tono-Pen central; less so when measured by Tono-Pen temporal periphery. Early detection of glaucoma and IOP follow-up in glaucoma patients may be done best by peripheral Tono-Pen measurements over the nonablated cornea.

[Familial parinaud oculo-glandular syndrome in cat-scratch disease].

Cat-scratch disease is manifested by subacute, regional lymphadenitis and occurs mainly in children. The causative agent is a pleomorphic, gram-negative bacillus, Bartonella henselae carried by asymptomatic cats. Parinaud oculoglandular syndrome is the most common ocular manifestation of this disease. It is characterized by unilateral conjunctivitis with polypoid granuloma, usually of the palpebral conjunctiva, and preauricular lymphadenopathy. The diagnosis is supported by a history of exposure to cats and is confirmed by positive serologic tests or positive PCR assay. The occurrence of more than 1 case of Parinaud syndrome in a family is rare. We describe 2 sisters with Parinaud oculoglandular syndrome, proven by serologic tests. They reported that they used to cuddle with their cats, among them a kitten. Because of the refractory conjunctivitis and signs of imminent periorbital cellulitis, they were treated with oral tetracycline with apparently good responses. We recommend asking about contacts with cats in any atypical conjunctivitis accompanied by regional lymphadenopathy, especially in young patients. Systemic antibiotics should be given when there is any suspicion of significant ocular involvement, if the patient is immunosuppressed, or if there are systemic manifestations of cat-scratch disease.