Frans Van De Velde

Characterization of Functional Changes in Macular Holes and Cysts

Precise characterization of functional loss in small retinal lesions is difficult with conventional techniques. Using the scanning laser ophthalmoscope, the authors evaluated functional changes and fixation behavior in 26 eyes with macular holes and 15 eyes with macular cysts. A dense scotoma was present over all macular holes; 24 had no detectable functional alteration at the margins of the hole, and fixation was above the horizontal meridian in all eyes. Nine eyes with cysts had no detectable functional loss over the cyst. Only two eyes had small areas of dense scotoma within the cyst area, and four had areas of relative scotoma. Fixation was central in all eyes. Characterization of functional changes is helpful in differentiating holes from cysts. Photocoagulation at the margin of the holes may result in further functional damage.

Importance of the vitreous in young diabetics with macular edema.

The authors assessed retrospectively the clinical records of 80 patients (137 eyes) with diabetic retinopathy who were 50 years of age or younger and who had undergone a vitreous examination. The group comprised 53 patients (91 eyes) with macular edema and 27 patients (46 eyes) without macular edema. Vitreous studies using the El Bayadi-Kajiura lens determined whether the posterior vitreous was attached to the retina in the macula. Forty (42.1%) of 91 eyes in the edema group and none (0%) of the 46 eyes in the nonedema group had a detached posterior vitreous. This difference was statistically significant, indicating that young diabetic patients with macular edema have a significantly higher rate of posterior vitreous detachment than those without macular edema.

Recording pattern reversal visual evoked response with the scanning laser ophthalmoscope

Abstract We recorded visual evoked responses (VERs) to alternating, checkerboard pattern stimuli using the scanning laser ophthalmoscope (SLO). Retinal position and focus of checkerboard stimuli were monitored on the SLO video monitor throughout testing. Checkerboard size, check size, and retinal positions were varied. Consistent with other, well‐established pattern reversal techniques, the SLO method produced: 1) reliable VERs with amplitudes of 2 to 10 microvolts, 2) maximum amplitudes at an intermediate check size for a fixed overall pattern size, and 3) variations in VER amplitude depending on stimulus retinal position relative to the fovea. Hence, the SLO‐VER technique would be useful for clinical VER measurements when precise retinal stimulus position and focus are desired.

Scanning Eye Movements in Homonymous Hemianopia Documented by Scanning Laser Ophthalmoscope Retinal Perimetry

Sparing or partial recovery of visual fields in hemianopic patients is frequently difficult to document. This is because when testing large field losses, the standard automated or manual visual field testing systems have limited fixation controls. Measured visual field recovery in these cases may not be real but instead may be due to an artifact such as scanning eye movement. This article illustrates a way to separate the actual visual field sparing from scanning eye movement artifact by using perimetry testing with the scanning laser ophthalmoscope (SLO). During the SLO perimetry, the examiner has a direct and magnified view of the retinal fixation locus. This direct view allows for the added ability to monitor the fixation stability during target presentation. When eye movements larger than 1° are noted, the examiner can repeat the trial. During static perimetry, our SLO records the retinal position of the fixation target at the end of the stimulus presentation and corrects scanning eye movements that occur during stimulus presentation. These special features enable us to identify when the apparent sparing of the visual field is due to the artifact of scanning. To demonstrate this, we selected the records of four hemianopic patients whose fields were examined by both standard perimetry and the SLO. We then compared the clinical visual fields with the SLO perimetry fields. One of the patients had a complete homonymous hemianopia on both the clinical perimetry and the SLO perimetry. A second patient was found by the SLO to have unstable fixation during testing. The SLO perimetry revealed that the apparent spared fields seen in standard perimetry were the result of eye scanning and not an actual enlargement of the visual field. Two other patients were confirmed by the SLO findings to have valid partial recovery of the visual field, one with and one without scanning eye movements. The advantages and limitations of SLO perimetry in analyzing hemianopic field sparing are discussed.

Inactive Subretinal Neovascuarizationin Age-related Macular Degeneration

Abstract Inactive subretinal new vessels (SRNVs), showing minimal leakage by fluorescein angiography and little progression, were observed in 15 eyes of 12 patients with age-related macular degeneration. In 8 (57%) of 14 eyes followed for longer than 6 months, the new vessels involuted and produced circumscribed areas of retinal pigment epithelium and choriocapillaris atrophy; 6 (43%) showed a further decrease in the fluorescein leakage during the follow-up period (average, 30.1 months). None of the new vessels organized into an exudative fibrovascular scar. Visual acuity was improved or unchanged during the entire follow-up period in 12 (86%) eyes and deteriorated in 2 (14%). Nine patients (75%) were 80 years of age or older; three (25%) were between 65 and 70 years of age. These observations suggested that SRNV showing minimal fluorescein leakage, particularly when it occurs in patients older than 80 years, do not require photocoagulation because they are usually self-limited.

Paradoxical Improvement of Visual Acuity in Macular Disease

Purpose: Improvement in visual acuity is often considered the best indicator of the effectiveness of a treatment in age-related maculopathy. However, during the course of the disease, the location of the patients’ preferred retinal locus of fixation may change. This can lead to an unexpected functional improvement, unrelated to treatment. Methods: From a running database of 1,369 retina patients, we identified 116 patients over 60 years of age when age-related maculopathy was diagnosed based on the following inclusion criteria: one study eye with an initial acuity of the logarithm of the minimum angle of resolution (logMAR) 0.7 or worse, a fellow eye with central fixation and a follow-up period of 3 years or more with precise documentation of the preferred retinal locus of fixation and scotoma distribution for both eyes using scanning laser ophthalmoscopy-based microperimetry. Results: We expected an improvement in the visual acuity in one eye (study eye) without the possibility of improvement due to previous or concurrent treatment in that eye. Twelve patients met the selection criteria. Over time, these patients had significant improvements in the visual acuity in the weaker study eye, characteristically accompanied by a concurrent decrease in visual acuity in the other eye, which initially had better visual acuity. Moreover, in all the study eyes, an unstable pseudo-central von Noorden fixation pattern evolved into a more stable eccentric preferred retinal locus. Conclusions: Visual acuity remains the gold standard for assessing visual functioning in age-related maculopathy when interpreted with caution. Improvements in visual acuity can occur solely due to the course of the disease in the other eye and as a result of its impact on binocular fixation characteristics. This finding has significant implications for low-vision rehabilitation and evaluation of various therapies in large long-term clinical studies.

Scanning laser retinoscopy: a new technique for evaluating optical properties of the cornea after refractive surgery

We present a new technique, scanning laser retinoscopy, to spatially resolve in two dimensions the optical aberrations and refractive power of the ocular media. For this purpose, the Maxwellian view of a confocal scanning laser ophthalmoscope (SLO) is configured to scan simultaneously the posterior and the anterior segment of the eye at different levels of prefocussing. This set-up allows retinal imaging and psychophysics through different optical zones of the cornea and lens. In addition, the size of the anatomical pupil can be dynamically controlled by adjusting the colinear infrared and visible light intensities of the illuminating system. In retinoscopic images we can see a part of the retina superimposed by distinctive patterns of shadows in the pupillary area. The variable patterns of shadows in the retinoscopic images change with the level of prefocussing of the SLO. The patterns are the result of local variations in refraction or wavefront aberrations within the lens and cornea. In cases of excimer laser refractive surgery, for example, scanning laser retinoscopy is able to distinguish between a treated central area, transition zone and peripheral cornea. As a corollary, we can document differences between excimer laser delivery systems and also correlate the retinoscopic images with the subjective complaints of refractive surgery patients. These include monocular diplopia, glare, loss of contrast sensitivity besides reduced visual acuity.

Indirect imaging of branch retinal vein occlusion using a scanning laser ophthalmoscope

Cystoid macular edema (CME) is a common cause of visual loss in several macular diseases including branch retinal vein occlusion (BRVO) [1]. To determine the severity of the visual impairment, it is important to evaluate the patient’s macular pathology. The necessary procedures can be enhanced with infrared (790 nm) indirect imaging using a digital scanning laser ophthalmoscope (SLO) F-10 (Nidek, Gamagori, Japan) with a new aperture; here we refer to this as the retro-mode. This apparatus can visualize retinal features undetectable by other methods. Herein we report the retinal findings evaluated by the retro-mode in a patient with BRVO. Case report