Determination of the excimer laser ablation rate in previously cross-linked corneas.

PURPOSE: To evaluate the need for and quantify the extent of nomogram adjustments to compensate for potential changes in the amount of effective corneal stroma ablated in previously cross-linked corneas. METHODS: Ex vivo porcine corneas were divided into two groups (the corneal cross-linking [CXL] group, n = 30; and the control group, n = 3): these experimental corneas underwent CXL including deepithelialization, instillation of riboflavin solution for 25 minutes, and ultraviolet-A irradiation at 9 mW/cm2 for 10 minutes. The control group was deepithelialized only. Four consecutive excimer laser ablations of 50 pm each were performed (AMARIS 750S; SCHWIND eye-tech-solutions, Kleinostheim Germany), and stromal bed thickness was measured with a built-in optical coherence pachymeter. To determine the potential influence of riboflavin, a third group (the riboflavin group, n = 12) underwent deepithelialization and instillation of riboflavin, but no ultraviolet-A irradiation. RESULTS: The mean individual ablation depth across the four ablations was significantly smaller in cross-linked corneas (-17%) when compared to untreated control corneas (P < .001). A consistent reduction of 12% was observed via a cumulative analysis when assessing the relative isolated effect of CXL on the ablation rate. There was no significant effect from riboflavin in the deeper ablations, except for the first ablation (68.6 + 1.1 mm [range: 1 to 50 pm]). This may be due to a measurement error in pachymetric readings due to the thin film of riboflavin on the surface that resists even extensive rinsing. CONCLUSIONS: CXL reduces the corneal ablation depth of excimer lasers in the anterior 200 pm of the porcine cornea by approximately 12%. Further clinical studies are needed to validate these findings in human corneas.

Cognitive performance in high-altitude climbers: a comparative study of saccadic eye movements and neuropsychological tests.

Impairment of cognitive performance during and after high-altitude climbing has been described in numerous studies and has mostly been attributed to cerebral hypoxia and resulting functional and structural cerebral alterations. To investigate the hypothesis that high-altitude climbing leads to cognitive impairment, we used of neuropsychological tests and measurements of eye movement (EM) performance during different stimulus conditions. The study was conducted in 32 mountaineers participating in an expedition to Muztagh Ata (7,546 m). Neuropsychological tests comprised figural fluency, line bisection, letter and number cancellation, and a modified pegboard task. Saccadic performance was evaluated under three stimulus conditions with varying degrees of cortical involvement: visually guided pro- and anti-saccades, and visuo-visual interaction. Typical saccade parameters (latency, mean sequence, post-saccadic stability, and error rate) were computed off-line. Measurements were taken at a baseline level of 440 m and at altitudes of 4,497, 5,533, 6,265, and again at 440 m. All subjects reached 5,533 m, and 28 reached 6,265 m. The neuropsychological test results did not reveal any cognitive impairment. Complete eye movement recordings for all stimulus conditions were obtained in 24 subjects at baseline and at least two altitudes and in 10 subjects at baseline and all altitudes. Measurements of saccade performances showed no dependence on any altitude-related parameter and were well within normal limits. Our data indicates that acclimatized climbers do not seem to suffer from significant cognitive deficits during or after climbs to altitudes above 7,500 m. We demonstrated that investigation of EMs is feasible during high-altitude expeditions.

High altitude retinal hemorrhages--an update.

Retinal hemorrhages represent a common phenomenon in eyes of high altitude climbers. In this review, we present an update about this entity, with focus on its pathophysiology and practical implications. Due to their delayed appearance in the course of an expedition, retinal hemorrhages are not predictive when assessing the risk for life-threatening complications related to hypobaric hypoxia. Consequences for ocular health depend greatly on the extent and localization of retinal bleedings, but are generally mild and reversible in healthy eyes.

Corneal melting two weeks after pterygium excision with topical mitomycin C: successfully treated with lamellar keratoplasty and amnion membrane transplantation.

PURPOSE: To report the management of a case of corneal melting two weeks after pterygium excision with intraoperative topical mitomycin C (MMC). METHODS: Case report. RESULTS: A 57-year-old male was referred to our Department for therapy of rapidly progressive corneal melting two weeks after primary pterygium surgery with MMC (0.2 mg/ml) in September 2009. Initial treatment consisted of topical and systemic immunosuppression along with topical antibiotics. Eight days after presentation, the patient underwent successful lamellar keratoplasty and amnion membrane transplantation. Subconjunctival injection of triamcinolone (40 mg/ml) and topical bevacizumab were used to manage the increased fibrovascular activity around the site of the former pterygium. CONCLUSION: Topical use of MMC during pterygium surgery may be related to serious postoperative complications such as progressive inflammatory corneal melting. The etiology may be multifactorial, which is related to MMC-induced inflammation and/or induced apoptosis. A therapeutic option is the described combination of systemic and local anti-inflammatory treatment along with lamellar keratoplasty and amniotic membrane transplantation. Adjunctive therapy may be needed if recurrence occurs.

Delayed appearance of high altitude retinal hemorrhages.

BACKGROUND: Retinal hemorrhages have been described as a component of high altitude retinopathy (HAR) in association with altitude illness. In this prospective high altitude study, we aimed to gain new insights into the pathophysiology of HAR and explored whether HAR could be a valid early indicator of altitude illness. METHODOLOGY/PRINCIPAL FINDINGS: 28 mountaineers were randomly assigned to two ascent profiles during a research expedition to Mt. Muztagh Ata (7546 m/24,751 ft). Digital fundus photographs were taken prior to expedition at 490 m (1,607 ft), during expedition at 4497 m (14,750 ft = base camp), 5533 m (18,148 ft), 6265 m (20,549 ft), 6865 m (22,517 ft) and 4.5 months thereafter at 490 m. Number, size and time of occurrence of hemorrhages were recorded. Oxygen saturation (SpO2) and hematocrit were also assessed. 79% of all climbers exhibited retinal hemorrhages during the expedition. Number and area of retinal bleeding increased moderately to medium altitudes (6265 m). Most retinal hemorrhages were detected after return to base camp from a high altitude. No post-expeditional ophthalmic sequelae were detected. Significant negative (SpO2 Beta: -0.4, p<0.001) and positive (hematocrit Beta: 0.2, p = 0.002, time at altitude Beta: 0.33, p = 0.003) correlations with hemorrhages were found. CONCLUSIONS/SIGNIFICANCE: When closely examined, a very large amount of climbers exhibit retinal hemorrhages during exposure to high altitudes. The incidence of retinal hemorrhages may be greater than previously appreciated as a definite time lag was observed between highest altitude reached and development of retinal bleeding. Retinal hemorrhages should not be considered warning signs of impending severe altitude illness due to their delayed appearance.

Use of intraoperative fourier-domain anterior segment optical coherence tomography during descemet stripping endothelial keratoplasty.

PURPOSE: To evaluate the intraoperative use of handheld Fourier-domain optical coherence tomography (OCT) during Descemet stripping automated endothelial keratoplasty (DSAEK) to assess the donor-host interface. DESIGN: Prospective, observational case series. METHODS: Six patients undergoing DSAEK surgery were included. OCT scans of the cornea were performed intraoperatively after insertion of the donor disc, after instillation of air in the anterior chamber beneath the disc, after vent incisions in the host cornea in each quadrant, following air-fluid exchange at the end of operation, and on day 1 after surgery. The central 3 mm of each cornea was scanned. The broadest gap between donor and host cornea (interface space) was measured. RESULTS: Adequate readings could be obtained from all patients without any complications. In 2 patients there was a decrease in the width of the interface space after each surgical step documented by the OCT scans. At the end of their operation, no interface space was detectable. In 2 patients, interface space disappeared after the vent incisions and did not reappear during the further course of the surgery. In further 2 patients the separation between the host and donor was still detectable at the end of the operation. All patients had no detectable interface gap on day 1. CONCLUSIONS: Handheld anterior segment OCT can be used to assess the host-donor interface in lamellar corneal transplantation surgery. Donor adherence can occur in spite of residual interface space at the end of surgery. Further studies should be conducted to answer the question of which surgical steps are useful in assisting with donor adhesion.

Nocturnal periodic breathing during acclimatization at very high altitude at Mount Muztagh Ata (7,546 m).

RATIONALE: Quantitative data on ventilation during acclimatization at very high altitude are scant. Therefore, we monitored nocturnal ventilation and oxygen saturation in mountaineers ascending Mt. Muztagh Ata (7,546 m). OBJECTIVES: To investigate whether periodic breathing persists during prolonged stay at very high altitude. METHODS: A total of 34 mountaineers (median age, 46 yr; 7 women) climbed from 3,750 m within 19-20 days to the summit at 7,546 m. During ascent, repeated nocturnal recordings of calibrated respiratory inductive plethysmography, pulse oximetry, and scores of acute mountain sickness were obtained. MEASUREMENTS AND MAIN RESULTS: Nocturnal oxygen saturation decreased, whereas minute ventilation and the number of periodic breathing cycles increased with increasing altitude. At the highest camp (6,850 m), median nocturnal oxygen saturation, minute ventilation, and the number of periodic breathing cycles were 64%, 11.3 L/min, and 132.3 cycles/h. Repeated recordings within 5-8 days at 4,497 m and 5,533 m, respectively, revealed increased oxygen saturation, but no decrease in periodic breathing. The number of periodic breathing cycles was positively correlated with days of acclimatization, even when controlled for altitude, oxygen saturation, and other potential confounders, whereas symptoms of acute mountain sickness had no independent effect on periodic breathing. CONCLUSIONS: Our field study provides novel data on nocturnal oxygen saturation, breathing patterns, and ventilation at very high altitude. It demonstrates that periodic breathing increases during acclimatization over 2 weeks at altitudes greater than 3,730 m, despite improved oxygen saturation consistent with a progressive increase in loop gain of the respiratory control system. Clinical trial registered with www.clinicaltrials.gov (NCT00514826).

Intraocular pressure during a very high altitude climb.

PURPOSE: Reports on intraocular pressure (IOP) changes at high altitudes have provided inconsistent and even conflicting RESULTS: The purpose of this study was to investigate the effect of very high altitude and different ascent profiles on IOP in relation to simultaneously occurring ophthalmic and systemic changes in a prospective study. METHODS: This prospective study involved 25 healthy mountaineers who were randomly assigned to two different ascent profiles during a medical research expedition to Mt. Muztagh Ata (7,546 m/24,751 ft). Group 1 was allotted a shorter acclimatization time before ascent than was group 2. Besides IOP, oxygen saturation (SaO(2)), acute mountain sickness symptoms (AMS-c score), and optic disc appearance were assessed. Examinations were performed at 490 m/1,607 ft, 4,497 m/14,750 ft, 5,533 m/18,148 ft, and 6,265 m/20,549 ft above sea level. RESULTS: Intraocular pressure in both groups showed small but statistically significant changes: an increase during ascent from 490 m/1,607 ft to 5,533 m/18,148 ft and then a continuous decrease during further ascent to 6,265 m/20,549 ft and on descent to 4,497 m/14,750 ft and to 490 m. Differences between groups were not significant. Multiple regression analysis (IOP-dependent variable) revealed a significant partial correlation coefficient of beta = -0.25 (P = 0.01) for SaO(2) and beta = -0.23 (P = 0.02) for acclimatization time. DISCUSSION: Hypobaric hypoxia at very high altitude leads to small but statistically significant changes in IOP that are modulated by systemic oxygen saturation. Climbs to very high altitudes seem to be safe with regard to intraocular pressure changes.

Changes of coagulation parameters during high altitude expedition.

PRINCIPLES: Data on changes of haemostatic parameters at altitudes above 5000 m are very limited. So far it is unknown, whether altered coagulation could contribute to the development of acute mountain sickness. METHODS: Thirty four healthy mountaineers were randomised to two acclimatisation protocols and undertook an expedition on Muztagh Ata (7549 m) in China. Tests were performed at five altitudes up to 6865 m. Haemostatic parameters, such as PT, aPTT, D-Dimer, APC-Resistance (APCR), von Willebrand Factor activity (RCo), ADAMTS-13 & C-Natriuretic Peptide (CNP) were assessed together with Lake Louise AMS score. RESULTS: D-Dimer significantly increased with increasing altitude (median 0.62 to 0.81 mcg/L, p <0.0001). During ascent, PT increased (83% to >100%) and APCR decreased significantly from 0.95 to 0.8 (p <0.01). Furthermore, a significant increase of aPTT (38 to 43 sec) was paralleled by significant changes of RCo (102% to 62%) (both p <0.001). There were no significant changes in ADAMTS-13 and CNP. No significant relationship between investigated parameters and AMS scores could be detected. When comparing the participants of the two acclimatisation protocols, there was an overall higher RCo in patients with a faster ascent protocol (p = 0.04). This was accompanied by lower ADAMTS-13 of the coagulation system in these patients (p = 0.04). CONCLUSIONS: Coagulation parameters change significantly during hypobaric hypoxia. Whereas we could detect no association between AMS scores and coagulation parameters, our results do show some parameters to be associated with an acclimatisation protocol and a successful ascent to the summit.

Dynamic contour tonometry: handheld versus slit-lamp-mounted.

PURPOSE: To compare the newly developed handheld dynamic contour tonometer (hh-DCT) with the established slit-lamp-mounted DCT (sl-DCT) in terms of agreement for intraocular pressure (IOP) and ocular pulse amplitude (OPA) measurements, intraobserver variability, and tonography effect. DESIGN: Evaluation of diagnostic technology. PARTICIPANTS: Fifty eyes of 50 healthy volunteers were examined with the hh-DCT and sl-DCT. METHODS: A paired t test was performed to analyze differences in IOP and OPA readings. Measurements were compared for bias and agreement according to the method of Bland and Altman. Intraclass correlation coefficients (ICCs) were calculated to compare intraobserver variability. A mixed model analysis was performed to assess a possible tonography effect. MAIN OUTCOME MEASURES: The differences in IOP and OPA measurements, intraobserver variability, and tonography effect between the hh-DCT and the sl-DCT were examined. RESULTS: No statistically significant differences in IOP (sl-DCT-hh-DCT: 0.1+/-1.43 mmHg, 95% confidence interval [CI], -0.31 to 0.5, P = 0.63) or OPA (sl-DCT-hh-DCT: -0.1+/-0.52 mmHg, 95% CI, -0.28 to 0.01, P = 0.08) measurements were detected. Bland-Altman analysis revealed a bias of 0.1 with the limits of agreement of IOP measurement differences ranging from -2.71 to +2.90 mmHg. With regard to IOP readings obtained by sl-DCT, hh-DCT overestimated IOPs less than 15.6 mmHg and underestimated IOPs more than 15.6 mmHg. ICCs calculated for IOP readings were 0.87 (95% CI, 0.8-0.92) for hh-DCT and 0.85 (95% CI, 0.78-0.90) for sl-DCT. ICCs for OPA readings were 0.86 (95% CI, 0.79-0.91) for hh-DCT and 0.87 (95% CI, 0.8-0.91) for sl-DCT. Comparing the ICCs revealed no statistically significant difference between the devices with regard to IOP and OPA measurements (P = 0.53 and P = 0.93, respectively). Mixed model analysis of 3 consecutive IOP measurements revealed a decrease in IOP of 0.5 mmHg after each measurement in both devices, which was not significant between the 2 methods (P = 0.68). CONCLUSIONS: IOP and OPA readings obtained by the novel hh-DCT were shown to be strongly concordant with measurements obtained by the sl-DCT device. The hh-DCT may be a valuable alternative to the sl-DCT in clinical practice.

Effect of ascent protocol on acute mountain sickness and success at Muztagh Ata, 7546 m.

Bloch, Konrad E., Alexander J. Turk, Marco Maggiorini, Thomas Hess, Tobias Merz, Martina M. Bosch, Daniel Barthelmes, Urs Hefti, Jacqueline Pichler, Oliver Senn, and Otto D. Schoch. Effect of ascent protocol on acute mountain sickness and success at Muztagh Ata, 7546 m. High Alt. Med. Biol. 10:25-32, 2009.-Data on acclimatization during expedition-style climbing to > 5000 m are scant. We evaluated the hypothesis that minor differences in ascent protocol influence acute mountain sickness (AMS) symptoms and mountaineering success in climbers to Muztagh Ata (7546 m), Western China. We performed a randomized, controlled trial during a high altitude medical research expedition to Muztagh Ata. Thirty-four healthy mountaineers (mean age 45 yr, 7 women) were randomized to follow one of two protocols, ascending within 15 or 19 days to the summit of Muztagh Ata at 7546 m, respectively. The main outcome measures, AMS symptom scores and the number of proceeding climbers, were assessed daily. Mean +/- SD AMS-C scores of 16 climbers randomized to slow ascent were 0.06 +/- 0.18, 0.26 +/- 0.08, 0.41 +/- 0.45, 0.53 +/- 0.77 at camps I (5533 m), II (6265 m), III (6865 m), and the summit (7546 m), respectively. Corresponding values in 18 climbers randomized to fast ascent were significantly higher: 0.17 +/- 0.23, 0.43 +/- 0.75, 0.49 +/- 0.36, and 0.69 +/- 0.54 (p < 0.008, vs. slow ascent in regression analysis accounting for weather-related protocol deviation). Climbers randomized to slow ascent were able to ascend according to the protocol without AMS for significantly more days than climbers randomized to fast ascent (p = 0.04, Kaplan-Meier analysis). More climbers randomized to slow ascent were successful in reaching the highest camp at 6865 m without AMS (odds ratio 9.5; 95% confidence interval 1.02 to 89). In climbers ascending to very high altitudes, differences of a few days in acclimatization have a significant impact on symptom severity, the prevalence of AMS, and mountaineering success. ClinicalTrials.gov Identifier NCT00603122.

Ocular pigmentation associated with clozapine.

A 55-year-old woman who was treated with long-term, high-dose clozapine for schizophrenia presented with bilateral decreased visual acuity. She had pigmentary changes affecting the cornea and the retina, as well as stellate cataract. Chlorpromazine use is known to produce similar changes, but this is the first report to our knowledge of pigmentation associated with clozapine use.

New insights into ocular blood flow at very high altitudes.

Little is known about the ocular and cerebral blood flow during exposure to increasingly hypoxic conditions at high altitudes. There is evidence that an increase in cerebral blood flow resulting from altered autoregulation constitutes a risk factor for acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) by leading to capillary overperfusion and vasogenic cerebral edema. The retina represents the only part of the central nervous system where capillary blood flow is visible and can be measured by noninvasive means. In this study we aimed to gain insights into retinal and choroidal autoregulatory properties during hypoxia and to correlate circulatory changes to symptoms of AMS and clinical signs of HACE. This observational study was performed within the scope of a high-altitude medical research expedition to Mount Muztagh Ata (7,546 m). Twenty seven participants underwent general and ophthalmic examinations up to a maximal height of 6,800 m. Examinations included fundus photography and measurements of retinal and choroidal blood flow, as well as measurement of arterial oxygen saturation and hematocrit. The initial increase in retinal blood velocity was followed by a decrease despite further ascent, whereas choroidal flow increase occurred later, at even higher altitudes. The sum of all adaptational mechanisms resulted in a stable oxygen delivery to the retina and the choroid. Parameters reflecting the retinal circulation and optic disc swelling correlated well with the occurrence of AMS-related symptoms. We demonstrate that sojourns at high altitudes trigger distinct behavior of retinal and choroidal blood flow. Increase in retinal but not in choroidal blood flow correlated with the occurrence of AMS-related symptoms.

High incidence of optic disc swelling at very high altitudes.

OBJECTIVES: To determine the incidence of optic disc swelling as a possible indicator of cerebral edema in a large group of healthy mountaineers exposed to very high altitudes and to correlate these findings with various clinical and environmental factors and occurrence of acute mountain sickness and high-altitude cerebral edema. METHODS: This multidisciplinary, prospective, observational cohort study was performed in 2005 within the scope of a medical research expedition to Muztagh Ata (7546 m [24,751 ft]) in Western Xinjiang Province, China. Twenty-seven healthy mountaineers aged 26 to 62 years participated. Medical examinations were performed in Switzerland 1 month before and 4 1/2 months after the expedition. Ophthalmologic examinations were performed at 4 high camps (maximum elevation, 6865 m [22,517 ft]). Optic disc status was documented using digital photography. Further assessments included arterial oxygen saturation and cerebral acute mountain sickness scores. RESULTS: Sixteen of 27 study subjects (59%) exhibited optic disc swelling during their stay at high altitudes, with complete regression on return to lowlands. Significant correlation was noted between optic disc swelling and lower arterial oxygen saturation (odds ratio, 0.86 per percentage of arterial oxygen saturation; 95% confidence interval, 0.81-0.92; P < .001), younger age (odds ratio, 0.95 per year; 95% confidence interval, 0.90-0.99; P = .03), and higher cerebral acute mountain sickness scores (odds ratio, 2.32 per 0.1 point; 95% confidence interval, 1.48-3.63; P < .001). CONCLUSION: Optic disc swelling occurs frequently in high-altitude climbers and is correlated with peripheral oxygen saturation and symptoms of acute mountain sickness. It is most likely the result of hypoxia-induced brain volume increase.

Is pseudophakia a risk factor for neovascular age-related macular degeneration?

PURPOSE: To examine the possible association between pseudophakia and neovascular age-related macular degeneration (AMD). METHODS: Reports of all patients undergoing fluorescein angiography in the authors' department over a 6-year period were retrospectively reviewed. Four hundred ninety-nine patients with recent onset of neovascular AMD in one eye and early age-related maculopathy (ARM) in the fellow eye were included in the study. Lens status (phakic or pseudophakic) in both eyes at the time of onset of neovascular AMD and the time between cataract surgeries (if performed) and onset of neovascular AMD were determined. RESULTS: There was no significant difference in lens status between eyes with neovascular AMD and fellow eyes with early ARM (115/499 [23.0%] vs. 112/499 [22.4%] pseudophakic; P = 0.88, odds ratio 1.035, 95% CI 0.770-1.391). Subgroup analysis revealed no difference between the groups with large drusen, small drusen, or pigmentary changes only (respectively, 20.3% vs. 19.6% pseudophakic, P = 0.92; 20.5% vs. 23.3% pseudophakic, P = 0.84; 33.3% vs. 31.7% pseudophakic, P = 1.0). Pseudophakic eyes with neovascular AMD had not been pseudophakic for a significantly longer period at the time of onset of neovascular AMD than their pseudophakic fellow eyes at the same time point (225.9 +/- 170.4 vs. 209.9 +/- 158.2 weeks, P = 0.27). CONCLUSIONS: The results do not support the hypothesis that pseudophakia is a major risk factor for the development of neovascular AMD.

Ophthalmologic findings and long-term course in patients with neurofibromatosis type 2.

PURPOSE: To evaluate ophthalmologic findings and long-term course in patients with neurofibromatosis type 2 (NF2). DESIGN: Retrospective observational case series. SETTING: Single-center institutional practice. STUDY POPULATION: Thirty referred patients with NF2 were enrolled from 1991 to 2003 and underwent at least one thorough neuroophthalmologic examination. Follow-up of 23 patients ranged from 4.3 to 12.5 years. MAIN OUTCOME MEASURES: Visual function, structural ocular abnormalities, onset and type of presenting NF2-related symptoms, and number of central nervous system tumors. RESULTS: Initial symptoms for patients with early-onset NF2 mostly comprised ophthalmologic symptoms (n = 7) and lower motor neuron extremity weakness (n = 6), as opposed to eighth nerve impairment (n = 11) in late disease onset. NF2-specific ocular findings were noted in 83% of all patients (94% childhood onset; 67% adult onset): 67% had cataracts, 40% epiretinal membranes, 3% hamartoma, 13% disk gliomas, and 27% optic nerve sheath meningiomas. Only 14% in the childhood-onset group-as opposed to 78% in the adult-onset group-sustained visual acuity of 1.0 in both eyes at final examination. Significantly more patients with early onset of symptoms developed multiple central nervous system tumors (P = .004) and showed a higher amount of NF2-specific findings (P = .015). CONCLUSIONS: Initial manifestations of NF2 differ between children and adults. NF2-specific ophthalmologic findings can help establish the diagnosis. Symptom onset at a young age is clearly a risk factor for marked disease progression. These patients should be carefully followed because survival rates have increased, and vision becomes increasingly important as the disease progresses.

Quantitative analysis of OCT characteristics in patients with achromatopsia and blue-cone monochromatism.

PURPOSE: To quantify optical coherence tomography (OCT) images of the central retina in patients with blue-cone monochromatism (BCM) and achromatopsia (ACH) compared with healthy control individuals. METHODS: The study included 15 patients with ACH, 6 with BCM, and 20 control subjects. Diagnosis of BCM and ACH was established by visual acuity testing, morphologic examination, color vision testing, and Ganzfeld ERG recording. OCT images were acquired with the Stratus OCT 3 (Carl Zeiss Meditec AG, Oberkochen, Germany). Foveal OCT images were analyzed by calculating longitudinal reflectivity profiles (LRPs) from scan lines. Profiles were analyzed quantitatively to determine foveal thickness and distances between reflectivity layers. RESULTS: Patients with ACH and BCM had a mean visual acuity of 20/200 and 20/60, respectively. Color vision testing results were characteristic of the diseases. The LRPs of control subjects yielded four peaks (P1-P4), presumably representing the RPE (P1), the ovoid region of the photoreceptors (P2), the external limiting membrane (ELM) (P3), and the internal limiting membrane (P4). In patients with ACH, P2 was absent, but foveal thickness (P1-P4) did not differ significantly from that in the control subjects (187 +/- 20 vs. 192 +/- 14 microm, respectively). The distance from P1 to P3 did not differ significantly (78 +/- 10 vs. 82 +/- 5 microm) between ACH and controls subjects. In patients with BCM, P3 was lacking, and P2 advanced toward P1 compared with the control subjects (32 +/- 6 vs. 48 +/- 4 microm). Foveal thickness (153 +/- 16 microm) was significantly reduced compared with that in control subjects and patients with ACH. CONCLUSIONS: Quantitative OCT image analysis reveals distinct patterns for controls subjects and patients with ACH and BCM, respectively. Quantitative analysis of OCT imaging can be useful in differentiating retinal diseases affecting photoreceptors. Foveal thickness is similar in both normal subjects and patients with ACH but is decreased in patients with BCM.

Optic nerve sheath meningiomas in patients with neurofibromatosis type 2.

OBJECTIVE: To determine the prevalence of optic nerve sheath meningiomas (ONSMs) in patients with neurofibromatosis type 2 (NF2). METHODS: An observational retrospective case series of 30 consecutive patients with NF2 referred to an academic ophthalmology unit from November 1, 1991, through August 31, 2003. Twenty-six patients were followed up for a mean of 93 months (range, 3-150 months). One individual was lost to follow-up, and 3 had been referred recently. Diagnosis of ONSM was made based on typical neuroradiologic and clinical features in 7 patients and on histologic criteria in 1. RESULTS: Eight of 30 patients harbored unilateral (n = 6) or bilateral (n = 2) ONSMs. Six ONSMs were diagnosed at initial examination, and 4 during follow-up. CONCLUSIONS: There is a strong association between ONSMs and NF2 that parallels the well-known association of optic nerve gliomas with NF1. Physicians should be aware of the possibility that patients with ONSMs may also have NF2.

The visual impact of fractionated stereotactic conformal radiotherapy on seven eyes with optic nerve sheath meningiomas.

BACKGROUND: Treatment of primary optic nerve sheath meningiomas (ONSMs) remains controversial. Although recent studies have suggested a favorable outcome of radiotherapy, controlled data on the efficacy of fractionated stereotactic conformal radiotherapy (SCRT) in primary ONSMs are still lacking. METHODS: Seven eyes treated with SCRT (total dose: 54 Gy) were compared with six eyes that were not treated because of patient or physician preference. The indication for intervention was deterioration of visual function with or without imaging evidence of tumor progression. Patients with secondary ONSMs and those with neurofibromatosis type 2 were excluded. The mean follow-up period was 57 months for the treated eyes and 61 months for the untreated eyes. RESULTS: Among the seven treated eyes, visual acuity improved in six, five of which sustained improvement of three or more Snellen lines. One eye deteriorated by two lines. Visual field improved in four eyes, remained stable in two, and deteriorated in one. Four untreated eyes showed worsening of visual acuity and two remained stable. Visual field deteriorated in three eyes and was stable in three. None of the untreated eyes experienced improvement in visual acuity or visual field. No complications of treatment were documented. CONCLUSIONS: In agreement with previous reports, these results indicate that SCRT is superior to observation in its impact on visual function in eyes with primary ONSMs.