Macular spectral-domain optical coherence tomography in patients with X linked retinoschisis.

AIM: To evaluate macular anatomy in patients with X linked retinoschisis (XLRS) using spectral-domain optical coherence tomography (SD-OCT). METHODS: Consecutive observational case series. Clinical features were obtained through retrospective chart review. Only eyes without prior surgical interventions and those scanned with SD-OCT were included. The OCT images were analysed. RESULTS: Fourteen eyes of seven males with XLRS scanned with SD-OCT, age 5 to 45 years, were identified. On clinical examination, stellate spoke-like cystic maculopathy was present in nine eyes, and an atrophic foveal lesion in five eyes. SD-OCT revealed cystoid spaces accounting for retinal splitting in the inner nuclear layer in 12 eyes, and outer plexiform layer in two eyes of one patient. A few small cysts, not accounting for the foveal splitting, were seen in the outer nuclear layer in four eyes and in the ganglion cell layer and/or nerve fibre layer in six eyes. CONCLUSIONS: SD-OCT localised the foveomacular retinoschisis in XLRS to the retinal layers deeper than the nerve fibre layer. In the present study, the foveomacular schisis was seen most frequently in the inner nuclear layer.

Characterization of urban air quality using GIS as a management system.

Keeping the air quality acceptable has become an important task for decision makers as well as for non-governmental organizations. Particulate and gaseous emissions of pollutant from industries and auto-exhausts are responsible for rising discomfort, increasing airway diseases, decreasing productivity and the deterioration of artistic and cultural patrimony in urban centers. A model to determine the air quality in urban areas using a geographical information system will be presented here. This system permits the integration, handling, analysis and simulation of spatial and temporal data of the ambient concentration of the main pollutant. It allows the users to characterize and recognize areas with a potential increase or improvement in its air pollution situation. It is also possible to compute past or present conditions by changing basic input information as traffic flow, or stack emission rates. Additionally the model may be used to test the compliance of local standard air quality, to study the environmental impact of new industries or to determine the changes in the conditions when the vehicle circulation is increased.

Transpupillary thermotherapy (TTT) of occult choroidal neovascularization: a retrospective, noncomparative case series of fifty-seven eyes.

PURPOSE: To evaluate the efficacy of transpupillary thermotherapy (TTT) for the treatment of occult choroidal neovascularization. METHODS: A retrospective, noncomparative case series of 57 eyes of 52 patients who presented with occult subfoveal CNV and were treated with TTT. RESULTS: 83% of eyes were either stable (+/- one line) or showed improvement in visual acuity. 83% of eyes showed stabilization of their exudative process after one TTT treatment as evidenced by resorption of subretinal and/or intraretinal exudate or hemorrhage. Nine percent of eyes developed classic CNV during the mean follow-up time of ten months. CONCLUSIONS: TTT appears to stabilize the exudative process in eyes with occult CNV. A prospective, sham-controlled, randomized study (TTT4CNV Clinical Trial) is currently underway to directly compare TTT to the natural history of occult CNV.

Optical coherence tomography after laser photocoagulation for clinically significant macular edema.

BACKGROUND AND OBJECTIVE: To demonstrate the utility of optical coherence tomography (OCT) for documenting an early response to laser photocoagulation in clinically significant macular edema (CSME) secondary to diabetes. PATIENTS AND METHODS: Five eyes of four patients were selected for review based on the diagnosis of CSME. All eyes had a clinical diagnosis of CSME based on slit lamp biomicroscopy. All eyes underwent focal/grid laser photocoagulation to areas of retinal thickening detected by OCT and clinical exam. Pre and post-treatment optical coherence tomograms were obtained for all patients. RESULTS: All eyes selected for review had an early positive response to focal laser photocoagulation. OCT was useful for demonstrating areas of retinal thickening prior to laser treatment. Serial macular maps demonstrated the resolution of retinal thickening after laser photocoagulation in all eyes. CONCLUSION: OCT is a useful tool for evaluating and documenting CSME both before and after focal/grid laser photocoagulation. OCT is capable of detecting an early positive response to photocoagulation for macular edema.

Transpupillary thermotherapy of occult subfoveal choroidal neovascularization in patients with age-related macular degeneration.

OBJECTIVE: To evaluate the efficacy of transpupillary thermotherapy for the treatment of occult subfoveal choroidal neovascularization (CNV) in patients with age-related macular degeneration. DESIGN: A retrospective, noncomparative case series. PARTICIPANTS: Sixteen eyes of 15 consecutive patients who presented with occult subfoveal choroidal neovascularization secondary to age-related macular degeneration. INTERVENTION: After informed consent was obtained, 16 eyes of 15 patients were treated with transpupillary thermotherapy. All patients underwent pretreatment fluorescein angiography and were deemed untreatable by the Macular Photocoagulation Study standard. Transpupillary thermotherapy was delivered using a diode laser at 810 nm. A variable spot size of 1.2 mm, 2.0 mm, or 3.0 mm was used depending on the size of CNV. The diode laser was delivered through a contact lens, and treatment was initiated in one spot for 60 seconds' duration at a power range between 360 and 1000 mW. The end point was an area of no visible color change to a light-gray appearance. MAIN OUTCOME MEASURES: In all eyes, outcome was assessed by Snellen chart visual acuity and clinical examination. In 10 of 16 eyes, preoperative and postoperative fluorescein angiography and optical coherence tomography were available. In the remaining 6 of 16 eyes, exudation was measured by postoperative clinical examination alone. RESULTS: Three eyes (19%) showed a two-or-more-line improvement in visual acuity over a period of 6 to 25 months. Mean follow-up was 13 months. Visual acuity remained stable (no change or one-line improvement) in nine treated eyes (56%). The remaining four eyes (25%) showed a decline (equal to one-line worsening or greater) in visual acuity. Fifteen eyes (94%) demonstrated decreased exudation on fluorescein angiography, optical coherence tomography, and/or clinical examination. CONCLUSIONS: Transpupillary thermotherapy shows no deleterious side effects in treating occult subfoveal choroidal neovascularization. A randomized, prospective study is necessary to evaluate treatment efficacy.

Evaluation of focal defects of the nerve fiber layer using optical coherence tomography.

OBJECTIVE: To analyze glaucomatous eyes with known focal defects of the nerve fiber layer (NFL), relating optical coherence tomography (OCT) findings to clinical examination, NFL and stereoscopic optic nerve head (ONH) photography, and Humphrey 24-2 visual fields. DESIGN: Cross-sectional prevalence study. PARTICIPANTS: The authors followed 19 patients in the study group and 14 patients in the control group. INTERVENTION: Imaging with OCT was performed circumferentially around the ONH with a circle diameter of 3.4 mm using an internal fixation technique. One hundred OCT scan points taken within 2.5 seconds were analyzed. MAIN OUTCOME MEASURES: Measurements of NFL thickness using OCT were performed. RESULTS: In most eyes with focal NFL defects, OCTs showed significant thinning of the NFL in areas closely corresponding to focal defects visible on clinical examination, to red-free photographs, and to defects on the Humphrey visual fields. Optical coherence tomography enabled the detection of focal defects in the NFL with a sensitivity of 65% and a specificity of 81%. CONCLUSION: Analysis of NFL thickness in eyes with focal defects showed good structural and functional correlation with clinical parameters. Optical coherence tomography contributes to the identification of focal defects in the NFL that occur in early stages of glaucoma.

Differentiation of degenerative retinoschisis from retinal detachment using optical coherence tomography.

OBJECTIVE: To assess the potential of optical coherence tomography (OCT) to differentiate retinoschisis from retinal detachment. Optical coherence tomography is a noninvasive, noncontact imaging method that produces high-resolution, cross-sectional images of ocular tissue. DESIGN: Retrospective case series. PARTICIPANTS: Thirteen eyes of 12 patients with the differential diagnosis of retinoschisis versus retinal detachment. METHODS: Differentiation between retinoschisis and retinal detachment was established from both ophthalmoscopic and OCT examinations. MAIN OUTCOME MEASURE: Ability of OCT to differentiate retinoschisis from retinal detachment was measured. RESULTS: Thirteen eyes of 12 patients with retinal elevation were examined with OCT. The cross-sectional view produced by OCT was effective in distinguishing retinoschisis from retinal detachment. Optical coherence tomography images of retinoschisis show a splitting of the neurosensory retina. The OCT images of retinal detachment show separation of full-thickness neurosensory retina from the retinal pigment epithelium band. The OCT images correlated with the clinical impression in all 13 cases. CONCLUSIONS: Based on this series of cases, OCT is a potentially useful new test that may be used to distinguish retinoschisis from rhegmatogenous retinal detachment.

Ozone-monitoring in Mendoza, Argentina: initial results.

A series of continuous ambient tropospheric ozone measurements were taken in Mendoza, Argentina, for a period of one year starting in November 1995. The data obtained were analyzed in terms of diurnal and annual variation. Indications were found of the strong impact of the mountain-valley circulation system, which ventilates and considerably cleans the air in Mendoza. The data are discussed in comparison with air pollution in the German city of Leipzig. In Mendoza, the high concentration of precursors and the strong solar radiation contribute to high levels of ozone. In fact, monitoring reveals considerably lower concentrations than in Leipzig, owing to the diluting effect of local meteorology. The low-level jet is mainly active during the summer. It lowers the peak mid-day ozone concentration and produces a temporary concentration increase at night. The Environmental Protection Agency standard of a maximum one-hour mean concentration of 0.250 mg ozone/m3 (125 ppb) is never reached, and the World Health Organization standard of 0.113 mg ozone/m3 (56.5 ppb) is only rarely exceeded during winter.

Treatment of relapsed cytomegalovirus retinitis with the sustained-release ganciclovir implant.

PURPOSE: Sustained-release ganciclovir implants are effective in delaying progression of newly diagnosed cytomegalovirus (CMV) retinitis. An uncontrolled case series was assembled to evaluate the efficacy of the intravitreal ganciclovir implant for patients with sight-threatening CMV retinitis who had previously failed to respond to intravenous ganciclovir and/or foscarnet. METHODS: Between August 1993 and March 1995, 72 eyes of 55 patients received intravitreal ganciclovir implants. Patients were examined monthly after implant surgery. RESULTS: A total of 56 eyes (77.8%) were available for evaluation after implant surgery. At the 1-month postoperative visit, 48 eyes (85.7%) of 38 patients had no progression. Implants failed to control progression at the 1-month visit in eight eyes (14.3%) of six patients receiving primary implants. A total of 32 eyes (57.1%) of 29 patients did not experience three-line loss of visual acuity through the follow-up period. The median time to three-line loss was 190 days from implantation. Four eyes (7.1%) developed visual acuity of 20/200 or worse by the 1-month follow up. The median time from implantation to development of visual acuity of 20/200 or less was 224 days. The median survival time was 376 days from study entry. The most common postoperative complication was retinal detachment, which was observed in 12 eyes receiving implants. Additional self-limiting complications included significant vitreous hemorrhage (three eyes) and hypotony maculopathy (two eyes). CONCLUSION: Ganciclovir implants were effective in delaying visual loss in a significant proportion of patients who failed ganciclovir or foscarnet therapy. A number of these patients, however, experienced visual loss. Although the implants can be effective as therapy for relapsed CMV retinitis, the efficacy does not appear to match that noted in initial CMV retinitis therapy.

Topography of diabetic macular edema with optical coherence tomography.

OBJECTIVE: This study aimed to develop a protocol to screen and monitor patients with diabetic macular thickening using optical coherence tomography (OCT), a technique for high-resolution cross-sectional imaging of the retina. DESIGN: A cross-sectional pilot study was conducted. PARTICIPANTS: A total of 182 eyes of 107 patients with diabetic retinopathy, 55 eyes from 31 patients with diabetes but no ophthalmoscopic evidence of retinopathy, and 73 eyes from 41 healthy volunteers were studied. INTERVENTION: Six optical coherence tomograms were obtained in a radial spoke pattern centered on the fovea. Retinal thickness was computed automatically from each tomogram at a total of 600 locations throughout the macula. Macular thickness was displayed geographically as a false-color topographic map and was reported numerically as averages in each of nine regions. MAIN OUTCOME MEASURES: Correlation of OCT with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity was measured. RESULTS: Optical coherence tomography was able to quantify the development and resolution of both foveal and extrafoveal macular thickening. The mean +/- standard deviation foveal thickness was 174 +/- 18 microns in normal eyes, 179 +/- 17 microns in diabetic eyes without retinopathy, and 256 +/- 114 microns in eyes with nonproliferative diabetic retinopathy. Foveal thickness was highly correlated among left and right eyes of normal eyes (mean +/- standard deviation difference of 6 +/- 9 microns). Foveal thickness measured by OCT correlated with visual acuity (r2 = 0.79). A single diabetic eye with no slit-lamp evidence of retinopathy showed abnormal foveal thickening on OCT. CONCLUSIONS: Optical coherence tomography was a useful technique for quantifying macular thickness in patients with diabetic macular edema. The topographic mapping protocol provided geographic information on macular thickness that was intuitive and objective.

Indocyanine green hyperfluorescence associated with serous retinal pigment epithelial detachment in age-related macular degeneration.

PURPOSE: Indocyanine green (ICG) angiography may improve visualization of choroidal neovascularization (CNV) associated with serous retinal pigment epithelial detachment (RPED) in age-related macular degeneration (AMD). The features of ICG hyperfluorescence associated with serous RPED and therapeutic effect of ICG-directed laser photocoagulation in eyes with serous RPED is evaluated. DESIGN: Retrospective review of all simultaneous fluorescein/ICG angiograms (n = 918) performed over an 18-month period to identify 44 eyes in 39 patients with serous RPED secondary to AMD on fluorescein angiography. PARTICIPANTS: Thirty-nine patients with AMD, aged 53 to 89 years, participated. INTERVENTION: Eyes were nonrandomly treated with ICG-directed laser photocoagulation or observation. MAIN OUTCOME MEASURES: Characteristics of ICG hyperfluorescence associated with a serous RPED are reviewed. Final visual acuity and anatomic appearance of the serous RPED are given. RESULTS: Twenty-three (52%) of the 44 eyes had an isolated serous RPED without obvious CNV, and 21 (48%) of the 44 eyes had a serous RPED associated with occult CNV on fluorescein angiography. Indocyanine green angiography demonstrated underlying CNV in 19 eyes (83%) with an isolated serous RPED and in all 21 eyes (100%) with serous RPED and occult CNV. The pattern of ICG hyperfluorescence revealed focal CNV in 15 eyes and plaque CNV in 4 eyes with an isolated serous RPED. In eyes with serous RPED and occult CNV, focal CNV and plaque CNV were noted with ICG in 8 and 13 eyes, respectively. No follow-up was available for two eyes. Twenty eyes were treated with ICG-directed laser photocoagulation. In these eyes, the visual acuity remained stable in 6 eyes (30%) and decreased in 14 eyes (70%). Twenty-two eyes were observed, and the visual acuity remained stable in 8 (36%), improved in 2 (9%), and decreased in 12 eyes (55%). CONCLUSIONS: Although ICG angiography may enhance visualization of CNV associated with serous RPED in AMD, ICG-directed laser treatment did not appear to improve visual acuity when compared with observed eyes in this series.

Densitometric approach to characterizing choroidal neovascular membranes.

The purpose of this study was to determine the nature of the relationship between density of indocyanine green (ICG) and the activity of occult choroidal neovascular membranes (CNVM) in patients with age-related macular degeneration (AMD) using ICG angiography. Ten eyes of ten patients with AMD and associated CNVM formation were retrospectively classified into either active or silent group on the basis of clinical outcome. Density of ICG for ICG leakage of CNVM was retrospectively determined from baseline ICG angiograms using an image analysis system. The means of relative density of the two groups were significantly different at five minutes after injection of ICG (p = 0.02). Densitometric analysis with ICG angiography may enable the discrimination of active from silent CNVM in patients with AMD, and thereby, prove useful in guiding clinical decision concerning treatment of these patients.

Characterization of epiretinal membranes using optical coherence tomography.

OBJECTIVE: To evaluate optical coherence tomography (OCT), a novel noncontact and noninvasive imaging technique, for the diagnosis and quantitative characterization of epiretinal membranes. METHODS: Optical coherence tomography is similar to an ultrasound B-scan, except that light rather than sound is used, which enables higher resolution. Over a 2-year period, OCT was used to examine 186 eyes of 160 patients who had a diagnosis of an epiretinal membrane. Optical coherence tomograms were correlated with visual acuity, slit-lamp biomicroscopy, fluorescein angiography, and funds photography. RESULTS: Based on OCT, the epiretinal membrane was clearly separated from the retina with focal points of attachment in 49 eyes and globally adherent (no observed separation) in 125 eyes. Globally adherent membranes were associated with the following features: macular pseudohole (32 eyes), a difference in optical reflectivity between the membrane and retina (65 eyes), and/or a visible membrane tuft or edge (92 eyes). The membrane was undetectable on OCT in 12 eyes. The membrane thickness (mean +/- standard deviation) was 61 +/- 28 microns in the 169 eyes in which the thickness could be measured with OCT. Mean central macular thickness measured with OCT correlated with visual acuity (R2 = 0.73). CONCLUSION: Optical coherence tomography was able to provide a structural assessment of the macula that was useful in the preoperative and postoperative evaluation of epiretinal membrane surgery. Quantitative measurements and the assessment of membrane adherence with OCT may be useful in characterizing the surgical prognosis of eyes with an epiretinal membrane.

Reproducibility of nerve fiber layer thickness measurements using optical coherence tomography.

PURPOSE: Optical coherence tomography (OCT) is a new technology that uses near-infrared light in an interferometer to produce approximately 10-microns resolution cross-sectional images of the tissue of interest. The authors performed repeated quantitative assessment of nerve fiber layer thickness in individuals with normal and glaucomatous eyes, and they evaluated the reproducibility of these measurements. METHODS: The authors studied 21 eyes of 21 subjects by OCT. Each subject underwent five repetitions of a series of scans on five separate occasions within a 1-month period. Each series consisted of three circular scans around the optic nerve head (diameters, 2.9, 3.4, and 4.5 mm). Each series was performed separately using internal (fixation with same eye being studied) and external (fixation with contralateral eye) fixation techniques. The eye studied and the sequence of testing were assigned randomly. RESULTS: Internal fixation (IF), in general, provides a slightly higher degree of reproducibility than external fixation (EF). Reproducibility was better in a given eye on a given visit than from visit to visit. Reproducibility as measured by intraclass correlation coefficients were as follows: circle diameter (CD), 2.9 mm, 0.51/0.57 (normal/glaucoma) (IF), 0.43/0.54 (EF); CD, 3.4 mm, 0.56/0.52 (IF), 0.43/0.61 (EF); CD, 4.5 mm, 0.53/0.43 (IF), 0.42/0.49 (EF). CONCLUSIONS: Nerve fiber layer thickness can be reproducibly measured using OCT. Internal is superior to external fixation; each circle diameter tested provides adequate reproducibility.

Optical coherence tomography of age-related macular degeneration and choroidal neovascularization.

OBJECTIVE: The authors used optical coherence tomography (OCT), a new technique for cross-sectional imaging of the retina, to morphologically study eyes with nonexudative and exudative age-related macular degeneration (AMD). In patients with untreated exudative AMD, OCT was compared with fluorescein angiography in the identification and classification of choroidal neovascularization (CNV). METHODS: Optical coherence tomography imaging is analogous to ultrasound, except that the use of light rather than sound enables higher longitudinal resolution with a noncontact and noninvasive measurement. Optical coherence tomography was performed on 391 patients with the clinical diagnosis of AMD and was compared with conventional clinical examination to establish the cross-sectional morphology of different lesions and to develop a classification scheme for CNV. Optical coherence tomograms and fluorescein angiograms then were reviewed and correlated independently in 90 eyes of 86 patients who had exudative AMD without previous laser treatment. RESULTS: Pigmentary changes, soft drusen, and detachments of the neurosensory retina and retinal pigment epithelium all had distinct presentations on OCT. Subretinal and intraretinal fluid caused changes in retinal thickness or elevation that could be quantified directly from the images. Choroidal neovascularization was evident in the tomograms as a thickening and fragmentation of a reflective layer, which corresponded to the retinal pigment epithelium and choriocapillaris. Changes in the reflection from this layer were observed during the progression of neovascularization, and after laser photocoagulation treatment. Classic CNV consistently presented with well-defined boundaries on OCT, whereas occult CNV had a variable cross-sectional appearance. CONCLUSIONS: Optical coherence tomography was useful in quantitatively evaluating subretinal and intraretinal fluid, assessing possible subfoveal involvement of neovascularization, and in monitoring CNV before and after laser photocoagulation. Optical coherence tomography was unable to detect CNV beneath serous pigment epithelial detachments. Optical coherence tomography may have potential in accurately defining the boundaries in a subset of angiographically occult CNV.

Optical coherence tomography of macular lesions associated with optic nerve head pits.

PURPOSE: Although optic pits were described more than a century ago, the pathogenesis and pathologic nature of the associated macular lesions remain controversial. The authors used the technique of optical coherence tomography (OCT) to further define the anatomic relation that exists between optic pits, macular schisis-like spaces, and macular detachments. METHODS: Four eyes of three consecutive patients with optic pit-related macular pathology were evaluated. Cross-sectional OCT images were correlated with findings from slit-lamp biomicroscopy and stereo fundus photography. All eyes previously had undergone unsuccessful photocoagulation to the temporal juxtapapillary retina. One eye had undergone vitrectomy and intraocular gas tamponade, resulting in partial resorption and displacement of the submacular fluid. RESULTS: Retinal edema and cystic degeneration were present, overlying macular neurosensory detachments in all four eyes. The most prominent edema was present in the outer retina at the level of the outer plexiform layer. This mimicked a true retinoschisis cavity, although bridging retinal elements were identifiable. A lesser degree of edema was present in the inner retina, predominantly located between the disc and fovea. In one eye, a lamellar hole was shown to be a defect in the outer neurosensory retina. In another eye, a macular detachment developed under a pre-existing schisis-like cavity. The schisis-like cavity or edematous retina communicated with the optic disc in all eyes, whereas none of the eyes demonstrated a direct connection between the macular detachment and optic pit. CONCLUSION: These findings support the concept of a bilaminar structure in which a macular detachment develops secondarily to a pre-existing schisis-like lesion consisting of severe outer retinal edema. Fluid may enter from the optic pit into the retinal stroma and not directly into the subretinal space, explaining the prolonged recovery and frequency of treatment failure after photocoagulation to the juxtapapillary retina.

Indocyanine green angiography and choroidal neovascularization obscured by hemorrhage.

BACKGROUND AND OBJECTIVE: To determine the use of indocyanine green (ICG) angiography in detecting choroidal neovascularization obscured by hemorrhage. STUDY/DESIGN: Indocyanine green angiography was performed on 20 consecutive patients who were suspected to have choroidal neovascular membranes (CNVs) that were obscured by subretinal or intraretinal hemorrhage on fluorescein angiography. The etiology of choroidal neovascularization was age-related macular degeneration. RESULTS: In all patients, ICG angiography was able to detect some choroidal neovascularization. The entire extent of the CNV was identified in 12 (60%) of these patients after ICG angiography was performed. In the remaining eight eyes (40%), the CNV still was obscured partially by a thick layer of hemorrhage. Difficulty in detection was due to thick subretinal hemorrhage, lipid exudate, and pigment. CONCLUSION: The authors conclude that ICG angiography is superior to fluorescein angiography in showing the presence and extent of CNVs associated with age-related macular degeneration that are almost entirely obscured by hemorrhage.

Indocyanine green angiography for recurrent choroidal neovascularization in age-related macular degeneration.

BACKGROUND AND OBJECTIVE: Recurrence of choroidal neovascular membranes (CNV) occurs frequently following laser photocoagulation. Recurrent CNV can be difficult to treat because they may not be well defined by fluorescein angiography. PATIENTS AND METHODS: The fluorescein and indocyanine green (ICG) angiograms of 58 eyes of 57 patients who presented with clinically suspected recurrence were evaluated retrospectively. RESULTS: In 14 eyes (24%), a well-defined recurrent CNV could be identified by evaluating the fluorescein angiogram. In 6 (14%) of the remaining 44 eyes, a well-defined recurrent CNV was identifiable by ICG angiography. CONCLUSION: A role for ICG angiography in the care of patients with suspected recurrent CNV is discussed.