Detailed measurements of the four extraocular rectus muscles' contribution to the perfusion of the anterior segment of the eye.

BACKGROUND/AIMS: Anterior segment ischaemia (ASI) is a rare but serious complication of strabismus surgery, which may be caused by damage to the anterior ciliary arteries that run along the rectus muscles. To avoid ASI, clinical praxis is to operate on a maximum of two rectus muscles at a time. The aim of this study was to perform a detailed study of the contribution of the four ocular rectus muscles to the perfusion of the anterior segment using laser speckle contrast imaging (LSCI). METHODS: The four rectus muscles were successively detached during enucleation in nine patients with suspected uveal melanoma. Perfusion of the anterior segment was monitored with LSCI during the detachment of each of the rectus muscles, and after the ophthalmic artery had been severed. RESULTS: Perfusion of the anterior segment, measured in the paralimbal tissue, decreased gradually as the four rectus muscles were detached, showing a decrease to 98% when the first (lateral rectus) muscle was detached, to 88% when the second (medial rectus), and 69% when the third (inferior rectus) muscles were detached. The decrease was more pronounced and statistically significant when the fourth (superior rectus) muscle was detached (to 28%, p=0.0102). CONCLUSION: LSCI is a valuable perfusion monitoring tool, as it has the capability to visualise the gradual decrease in anterior segment perfusion as the rectus muscles are successively detached. Further studies are needed to determine how many rectus muscles can be safely detached during strabismus surgery without risking ASI.

Pre- and Postnatal Damage to the Retro-Geniculate Visual Pathways Cause Retinal Degeneration Predictive for Visual Function.

To increase the understanding of the relationship between structure and function in individuals with damage to the brain from different stages of maturation of the visual system, we examined 16 teenagers and young adults. We used diffusion-weighted magnetic resonance imaging (MRI) and fiber tractography of the optic radiation (OR) and optical coherence tomography (OCT) of the peripapillary retinal nerve fiber layer (pRNFL) and the ganglion cell layer + inner plexiform layer (GC+IPL) in the macula. Visual field (VF) function was assessed with the Humphrey Field Analyzer (HFA). Injuries to the immature OR were associated with thinning of the pRNFL and GC+IPL, and corresponding VF defects irrespectively of timing of the lesion. However, in cases with bilateral white-matter damage of immaturity (WMDI) we noticed a well preserved central VF despite a very thin GC+IPL. We speculate that this is due to plasticity in the immature visual system. Similar results were not noticed among cases with unilateral damage, acquired pre- or postnatally, in which the central VF was affected in most cases. OCT has proved to be a valuable targeted tool in children with damage to the retro-geniculate visual pathways, and that focal thinning of the GC+IPL predicts VF defects. This brief research report includes a review of four previously published papers. In addition, we present one new case and apply a recently developed classification system for CVI. The classification was applied on cases with bilateral WMDI to investigate its relation to retinal structure.

Making a Correct Diagnosis of Glaucoma: Data From the EMGT.

PRéCIS:: A correct diagnosis of glaucoma established at initial visits. PURPOSE: It has been suggested that a diagnosis of glaucoma cannot be certain until progression has been demonstrated. Our aim was to evaluate the correctness of a glaucoma diagnosis established after 2 initial visits. PATIENTS AND METHODS: Patients included in the Early Manifest Glaucoma Trial (EMGT) who had continued follow-up for at least 15 years were included in this analysis. The patients had been recruited primarily through a population screening and were diagnosed with glaucoma if the Glaucoma Hemifield Test was outside normal limits in the same sector at two consecutive visits. A Glaucoma Hemifield Test classification of borderline was also diagnostic if corresponding optic disc findings were present. At least one of the following criteria had to be fulfilled during follow-up to confirm the initial diagnosis: (1) visual field progression in at least one eye according to the EMGT criterion; (2) development of manifest glaucoma in an initially ineligible fellow eye; (3) optic disc progression in at least one eye; (4) optic disc hemorrhages in at least 1 eye. RESULTS: Of the 255 patients included in the EMGT, 117 were followed for at least 15 years, representing 147 eyes eligible for our study. During follow-up, 134 eyes (91%) showed visual field progression, and, of the remaining 13 eyes, only 4 (3%) did not fulfill any of the criteria to confirm the diagnosis. CONCLUSIONS: A diagnosis made applying strict criteria to 2 initial visual field tests, supported by optic disc findings if visual field findings were borderline, was almost always correct.

Detection of glaucoma progression by perimetry and optic disc photography at different stages of the disease: results from the Early Manifest Glaucoma Trial.

PURPOSE: To compare the earliest detection of progression in visual fields and monoscopic optic disc photographs at different stages of manifest glaucoma. METHODS: This study evaluated 306 eyes in 249 patients with manifest open-angle glaucoma included in the Early Manifest Glaucoma Trial (EMGT). All patients in the trial were followed up regularly by standard automated perimetry and monoscopic optic disc photography, and the median follow-up time was 8 years. Progression was assessed in series of optic disc photographs and in series of visual fields using glaucoma change probability maps and the predefined EMGT progression criterion. The proportion of progressions detected first in visual fields and the proportion detected first in optic disc photographs were compared at different stages of glaucoma severity defined by the perimetric mean deviation (MD) of the baseline visual field. RESULTS: Assessment of 210 eyes with early visual field loss, 83 eyes with moderate field loss, and 13 eyes with advanced field loss showed that, among the eyes exhibiting progression, the progression was detected first in the visual field in 80%, 79% and 100%, respectively. The predominance of visual field progressions at all stages was still apparent when using narrower (3-dB) MD intervals for staging. CONCLUSION: In the EMGT material on eyes with manifest open-angle glaucoma, the initial progression was detected much more often in the visual field series than in the optic disc photographs at all stages of disease.

Structural and Functional Progression in the Early Manifest Glaucoma Trial.

PURPOSE: To elucidate the temporal relationship between detection of glaucomatous optic disc progression, as assessed by fundus photography, and visual field progression. DESIGN: Prospective, randomized, longitudinal trial. PARTICIPANTS: Three hundred six study eyes with manifest glaucoma with field loss and 192 fellow eyes without any field defect at the start of the trial, from a total of 249 subjects included in the Early Manifest Glaucoma Trial (EMGT), were assessed. METHODS: Evaluation of visual field progression and optic disc progression during an 8-year follow-up period. Three graders independently assessed optic disc progression in optic disc photographs. Visual field progression was assessed using glaucoma change probability maps and the EMGT progression criterion. MAIN OUTCOME MEASURES: Time to detection of visual field progression and optic disc progression. RESULTS: Among study eyes with manifest glaucoma, progression was detected in the visual field first in 163 eyes (52%) and in the optic disc first in 39 eyes (12%); in 1 eye (0%), it was found simultaneously with both methods. Among fellow eyes with normal fields, progression was detected in the visual field first in 28 eyes (15%) and in the optic disc first in 34 eyes (18%); in 1 eye (1%), it occurred simultaneously. CONCLUSIONS: In eyes with manifest glaucoma, progression in the visual field was detected first more than 4 times as often as progression in the optic disc. Among fellow eyes without visual field loss at baseline, progression was detected first as frequently in the optic disc as in the visual field.