Scanning laser ophthalmoscopy in the retromode in diabetic macular oedema

Purpose: To determine the validity of scanning laser ophthalmoscopy in the retromode (RM-SLO) versus other imaging modalities in the diagnosis of diabetic macular oedema (DME). Methods: Two hundred and sixty-three eyes were examined. Inclusion criteria were any stage of untreated or treated diabetic retinopathy and four imaging modalities of the macula carried out on the same day: time domain optical coherence tomography (OCT), fundus autofluorescence (FAF), RM-SLO and fluorescein angiography (FA). Two masked retinal specialists independently graded all images. Agreement between RM-SLO and OCT, FA and FAF in evaluating the presence and patterns of DME was evaluated by kappa statistics, sensitivity, specificity, observed proportional agreement, and proportional agreement in positive and negative cases. Results: The agreement in evaluating the presence/absence of DME between RM-SLO and OCT, FA and FAF was good: κ?=?0.73 (confidence interval; CI, 0.64-0.83), κ?=?0.71 (CI, 0.61-0.81) and κ?=?0.73 (CI, 0.63-0.83), respectively. The agreement in evaluating cystoid pattern of DME was almost perfect between RM-SLO and OCT, RM-SLO and FA, κ?>?0.8; and good between RM-SLO and FAF, κ?>?0.7. The agreement in evaluating the presence/absence of subfoveal neuroretinal was almost perfect between RM-SLO and OCT (κ?=?0.83; 95% CI, 0.70-0.96). Subfoveal neuroretinal detachment did not show any specific pattern on FA or FAF. Sensitivity and specificity of RM-SLO in evaluating DME was 97.7% and 71.9% versus OCT, 97.4% and 68.1% versus FA and 96.1% and 73.3% versus FAF. Retinal thickness of 233?μm represented the cut-off value to define DME by RM-SLO. Conclusions: The combined use of non-invasive imaging techniques can improve the diagnostic interpretation of different aspects of DME.     

Scanning laser ophthalmoscopy in an elderly Indian population

Purpose: To study optic nerve head (ONH) characteristics using scanning laser ophthalmoscopy, Heidelberg retina tomograph (HRT), in an elderly population.

Methods: A population-based, cross-sectional study included 1460 eyes of 1460 consecutive, subjects >60 years, in North India. All subjects underwent a detailed ophthalmic evaluation and imaged on HRT. Stereometric parameters, Moorfields regression analysis (MRA) and discriminant function analysis were analyzed. Correlation between ONH parameters and disc area, age, sex, and intraocular pressure was analyzed.

Results: Disc size had a normal Gaussian distribution (2.22 ± 0.48 mm²), but all other stereometric parameters showed a wide variation.

MRA found 1320 (90.4%) eyes within normal limits, 71 (4.86%), borderline limits, and 69 (4.73%) outside normal limits.

Comparison of eyes meeting International Society of Geographical and Epidemiological Ophthalmology criteria for a glaucoma suspect, C:D > 0.7, with those that did not show a statistically significant difference in the cup area, rim area, rim disc ratio, and cup volume (p = 0.02, 0.02, 0.02, 0.03, respectively).

An Intraocular pressure (IOP) ≥21 mmHg was seen in 3.01%, and only 12 eyes out of 1460, 0.82%, had an IOP ≥21 mmHg and a cup:disc ratio of more than 0.7. A van Herick estimation of < Grade 3 was seen in 19.4%

Conclusions: Stereometric parameter data, MRA, and clinical examination in this population at high risk for glaucoma found that about 10% of individuals over 60 years of age could be classified as glaucoma suspects and would need further evaluation.     

Scanning laser ophthalmoscopy of choroidal neovascularisation using indocyanine green

Background: Choroidal neovascularisation is an important cause of visual loss in age-related macular degeneration. Visualisation of these choroidal abnormalities with fluorescein angiography may be difficult, particularly if there is haemorrhage, excessive pigment, or excessive fluorescence. We report on our experience with indocyanine green (ICG) angiography in demonstrating choroidal neovascularisation.
Method: Patients with suspected choroidal neovascularisation were assessed with indocyanine green angiography using the Rodenstock Scanning Laser Ophthalmoscope and results recorded on a videotape. Fluorescein angiograms were also obtained in a similar fashion. The angiograms were then compared.
Results: In some instances ICG angiography was able to demonstrate the margins and structure of choroidal neovascular membranes more clearly than fluorescein, particularly in the presence of haemorrphage, excessive fluorescence and blocked fluorescence. However, there were instances where it was difficult to interpret the choroidal abnormalities found. Some illustrative cases are discussed.
Conclusion: We conclude that ICG angiography is a useful adjunct to fluorescein angiography in detection and delineation of choroidal neovascularisation, but that further study is needed.     

Scanning laser ophthalmoscopy for early diagnosis of vitreoretinal interfase syndrome

Purpose: To describe the angiographic signs found using scanning laser ophthalmoscopy for the early diagnosis of vitreoretinal interface syndrome.This method is useful to visualize the inner retinal layers, being more sensitive than fundus biomicroscopy.Material: 61 patients with vitreoretinal interfase syndrome were evaluated. All of them had evidence of this disease using scanning laser ophthalmoscopy but four patients were referred without diagnosis of vitreoretinal interfase syndrome. These patients showed no biomicroscopic signs and diagnosis was made with SLO.Methods: Confocal scanning infrared laser ophthalmoscope (Heidelberg Retinal Angiograph assembled by Heidelberg Engineering). This SLO uses an infrared diode laser source of 795 nm. Conclusion: Patients included were referred with another diagnosis and with this method the correct diagnosis was made. In conclusion scanning laser ophthalmoscopy allows early diagnosis of this pathology for follow-up and treatment.     

Scanning laser ophthalmoscope findings in acute macular neuroretinopathy

PURPOSE: The typical reddish-brown retinal lesions of acute macular neuroretinopathy are difficult to detect. We demonstrate a role for scanning laser ophthalmoscopy in the diagnosis of acute macular neuroretinopathy. METHODS: Observational case report. We used scanning laser ophthalmoscopy in a 23-year-old woman with acute macular neuroretinopathy. RESULTS: In contrast to biomicroscopy, color fundus photography, and red-free fundus photography, scanning laser ophthalmoscopy precisely disclosed the size of the lesions within the macula. Microperimetry showed absolute scotomata corresponding to the macular lesions. CONCLUSION: Scanning laser ophthalmoscopy enhances the visibility of the retinal lesions in acute macular neuroretinopathy. The lesion size can be determined more precisely, and follow-up of patients is more accurate compared with conventional techniques.     

Blue on yellow perimetry with scanning laser ophthalmoscopy in patients with age related macular disease

BACKGROUND/AIM: The loss of short wavelength sensitive (SWS) cone mechanism sensitivity is related to severe vision loss in patients with age related maculopathy (ARM). A case-control study of patients with ARM and age matched controls was performed, using blue on yellow static perimetry. METHODS: A bright yellow background at 594 nm isolated the responses of short wavelength cone mechanisms to 458 nm targets. A scanning laser ophthalmoscope produced stimuli and provided real time, simultaneous fundus illumination. The macula was probed with 16 Goldmann IV targets, 1-10 degrees from fixation, using a staircase method. RESULTS: 24 patients with non-exudative ARM were matched to 24 subjects with normal fundus appearance. SWS cone pathway sensitivity for macular targets was significantly reduced in the patients with ARM compared to normals--15.45 (SD 4.56) dB v 17.22 (0.28) dB, respectively (p<0.0005). There was not only a diffuse loss of sensitivity in ARM patients, but also a localised loss of sensitivity over drusen (p<0.025). Neither the mean age, 69 (8) years, nor the mean visual acuity differed between groups, logMAR 0.09 (0.10) v 0.05 (0.06) for ARM patients v normals, respectively. Patients with soft drusen had lower sensitivity than those with hard drusen (p<0.05). CONCLUSION: A loss of SWS cone pathway sensitivity occurred in most patients with early ARM, despite good visual acuity, demonstrating a loss of visual function that cannot be attributed to ageing changes. The loss of sensitivity, despite good visual acuity, included both a diffuse loss and localised losses.     

Scanning laser tomography of full thickness idiopathic macular holes

AIM: We used a retinal tomographic analyser to study the profile of the retinal surface in patients with stage 3 and 4 idiopathic macular holes, to attempt to elucidate the direction of forces present. METHODS: The Heidelberg retina tomograph was used to acquire a three-dimensional tomographic image of the macula in each eye of 21 consecutive patients with full thickness macular hole. RESULTS: The surface profile showed an elevated rim around the 24 macular holes imaged, with a gently sloping outside edge and a steeply sloping inside edge. In addition, a ring of elevated tissue around the edge of the hole was observed in all the holes and also in two of the fellow 'normal' eyes. This ring of elevated tissue was presumed to represent a ring of persistent vitreo-retinal traction around the fovea in the presence of a perifoveal posterior vitreous detachment. This is consistent with antero-posterior traction persisting in stage 3 and 4 full thickness macular holes. The mean ring diameter was 480 mum, when present in the fellow eye but was 950 microm in the presence of a macular hole, which we argue is suggestive of centrifugal displacement of retinal tissue on the formation of a stage 3 macular hole and provides evidence for tangential traction. CONCLUSION: We suggest that antero-posterior traction forces are the primary cause of full thickness macular holes, with these forces persisting in stage 3 and 4 macular holes, while tangential forces serve to enlarge the hole at this later stage.     

Contribution of scanning laser ophthalmoscopy to the functional investigation of subjects with macular holes

A study was designed to validate a functional investigation performed with the scanning laser ophthalmoscope before surgery for macular holes in 12 eyes: The assessment included fundus examination, a functional examination resulting in evaluation of the preferred retinal lows, visual acuity and recording of visual evoked potentials. The preferred retinal locus was evaluated by presenting a small square area, and visual acuity was determined by means of calibrated figures. The visual evoked potentials were evoked by three alternating checkerboards (check size, 30, 2 Hz) centered over the hole and seen at an angle of 6.5 × 6.5°, 2.5 × 2.5° and 6.5 × 6.5° with central exclusion of 2.5 × 2.5°. The appearance of the fundus visualized by scanning laser ophthalmoscopy consisted of a clear central disk corresponding to the hole, surrounded by a very dark ring, associated with a second, less dark ring with unclear margins. Fixation was unstable in one case with a visual acuity of 20/70. In 11 cases, fixation was localized to the superior retina with a visual acuity superior to 20/70. The visual evoked potentials evoked by 6.5 × 6.5° were discernible in all 12 eyes; visual evoked potential by annular stimuli were discernible in 11 cases. The 2.5 × 2.5° stimulus evoked no response in eight cases, proving the area of the hole was nonfunctional. A response was recorded in the four other cases, where the dimension of the holes was less than 2°. The results of this scanning laser ophthalmoscopic assessment demonstrated a precise evaluation of the residual macular function in the cases of full-thickness macular holes.Abbreviations SLO scanning laser ophthalmoscope     

Radiating retinal folds detected by scanning laser ophthalmoscopy using a diode laser in a dark-field mode in idiopathic macular holes

· Background: The pathogenesis of idiopathic macular hole is unclear. We studied the morphologic features of idiopathic macular holes using a modification of the scanning laser ophthalmoscope (SLO). · Methods: Seventy-two eyes of 57 patients with macular hole (40 women, 17 men; age 66.1±6.4 years, mean±SD) were included in this study. The macular holes were classified according to the Gass classification (1988). The changes around the macular holes were recorded by SLO using both a confocal aperture with a helium-neon laser (633 nm) and a ring aperture (dark-field mode) with a diode laser (780 nm) to detect fine morphologic features. · Results: We successfully observed minute retinal wrinkling, i.e., radiating striae (fold type) and a dome configuration (dome type), around the macular holes using the SLO dark-field mode with a diode laser, which provides a deeper retinal image because of the longer wavelength laser and the indirect mode. A helium-neon laser with a confocal aperture sometimes failed to disclose the fine retinal wrinkles. Most of the stage 2 macular holes were of the fold type. The smaller the hole, the higher the prevalence of the fold type. As the holes progressed in size, the prevalence of the dome type increased. The radiating retinal folds disappeared after successful vitreous surgery. · Conclusion: The SLO dark-field mode with a diode laser might be useful for clear observation of fine retinal features around macular holes. The retinal folds probably indicate the presence of traction on the macula and hence may be good markers for macular repair after vitreous surgery. Received: 28 February 1997 Revised version received: 16 July 1997 Accepted: 18 August 1997     

Multifocal retinal contraction in macular pucker analyzed by combined optical coherence tomography/scanning laser ophthalmoscopy

PURPOSE: To characterize the topography of macular pucker using coronal plane imaging in vivo, and correlate this with transverse optical coherence tomography (OCT) to assess the relationship between topographic features and severity of disease. METHODS: Forty-four eyes with macular pucker underwent full ophthalmologic evaluation including B-scan ultrasonography as well as coronal and transverse plane imaging with combined OCT/scanning laser ophthalmoscopy (SLO). RESULTS: Posterior vitreous detachment was present in 37/44 eyes (84.1%) by ultrasound. Multiple foci of retinal contraction were detected in 20/44 eyes (45.5%) by coronal plane OCT/SLO. Intraretinal cysts were present in 6/9 (66.7%) eyes with three or four contraction centers as compared to 10/35 (28.6%) eyes with one or two contraction centers (P = 0.05). Eyes with three or four contraction centers had significantly (P = 0.05) thicker maculae (369 +/- 98 microm) compared to those with one or two contraction centers (297 +/- 110 microm). CONCLUSION: Coronal plane imaging detected multifocality in nearly half of eyes with macular pucker. Eyes with multiple retinal contraction centers had greater retinal damage compared to eyes with one or two contraction centers. Multifocal retinal contraction may have clinical significance in that it may impact on prognosis and management.     

Differential imaging in scanning laser ophthalmoscopy

Differential imaging may be useful for understanding pathologies of the choroid. We use a prototype scanning laser ophthalmoscope capable of simultaneous multiple wavelength imaging to record fundus images. The advantages of simultaneous acquisition compared to serial acquisition are, reduced image capture times, and image registration is not required.The system is run under non-confocal conditions in using slit apertures with a width of up to 600 m. The laser lines launched into the SLO were the 633 nm line of a HeNe- laser, and the 815 nm line from a tunable (740 nm to 840 nm) cw Ti:Sapphire-laser. The difference in absorption at these two wavelengths is used to produce a differential image. We compare conventional imaging with differential spectral imaging for viewing the choroidal vessels. Qualitative results show the contrast of choroidal vessels in differential imaging is improved compared with normal imaging in the region of the optic disk and for the level of pigmentation in the subjects examined.     

Analysis of digital scanning laser ophthalmoscopy fundus autofluorescence images of geographic atrophy in advanced age-related macular degeneration

BACKGROUND: Fundus autofluorescence (AF) imaging using confocal scanning laser ophthalmoscopy (cSLO) has been shown to be superior to fundus photography or angiography for delineating areas of geographic atrophy (GA) in retinal pigment epithelium (RPE) and for recording variation over time. We have evaluated a method for automated computerized detection and quantitation of RPE atrophy. METHODS: AF images in vivo were recorded with a confocal scanning laser ophthalmoscope (exc. 488 nm, em. >500 nm; Heidelberg Retina Angiograph). The intensity of AF in atrophic areas was markedly decreased. Two independent readers analysed these areas in 24 right eyes manually by outlining GA areas using a mouse-driven arrow (method A) and automatically by image analysis software (Global Lab Image/2) after subjective adjustment of thresholding (method B). Agreement between observers and between methods A and B was assessed by the Bland-Altman design for method-comparison studies. RESULTS: Larger areas were measured using method A than B by both readers (agreement A/B: reader 1 mean difference 1.04 mm, 95% CI [0.66,1.42]; reader 2 mean difference 0.62 mm, 95% CI [0.43,0.81]). The agreement between the readers was mean difference 0.39 mm (95% CI [0.02,0.76]) for A and mean difference -0.03 mm (95% CI [-0.23,0.18]) for B. Features making the delineation of borders of GA difficult included large choroidal vessels with autofluorescent properties in the GA area and media opacities. CONCLUSIONS: Fundus AF cSLO imaging provides a reliable means to delineate areas of GA. The automated image analysis allows more accurate detection and quantitative documentation of atrophic areas than manual outlining. This method will be useful in longitudinal natural history studies and for monitoring effects of future therapeutic interventions to slow down GA progression in patients with advanced atrophic ARMD and other retinal diseases associated with outer retinal atrophy.