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Peri-operative Investigations
Published in Pradeep Venkatesh, Handbook of Vitreoretinal Surgery, 2023
Multifocal ERG [MfERG], as the name suggests, is a special form of ERG in which the retina is stimulated at multiple points in a unique pattern and the electrical response is recorded. Unlike conventional ERG, in which the recording obtained indicates the response of the entire retina, in MfERG, the response obtained indicates a combination of the response solely from the stimulated retina. Three waves are noted in an MfERG recording, N1, P1, and N2, and these are generated by the photoreceptors, Mueller cells, and inner retina, respectively. Preoperative MfERG may be useful in predicting visual outcome following surgery for conditions such as vitreomacular traction, myopic foveoschisis, and resistant diabetic macular edema. Microperimetry is a psychophysical test that allows testing of retinal sensitivity at some prespecified points on the retina. It is also designated as fundus-guided perimetry. Because the fixation pattern [stable, relatively unstable, and unstable] can be documented and the testing points can also be customized in newer versions, microperimetry may be a useful investigation to prognosticate the visual recovery following surgery for conditions such as macular hole, resistant diabetic macular edema, choroidal coloboma, and optic disc pit maculopathy.
Practical approach to macular translocation with 360° peripheral retinectomy
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
John P Denny, Mark T Cahill, Sharon F Freedman, Cynthia A Toth
Ancillary testing aids in the determination of a specific patient’s suitability for MT360.20 Fixation testing, fluorescein angiography, and optical coherence tomography (OCT) are helpful in the preoperative evaluation. Fixation testing provides important functional information regarding the fovea. Patients with poor fixation have likely irreversibly lost foveal photoreceptor function. As a result, moving the fovea to a new site may not improve visual function. Fixation is tested either with a small beam of light during biomicroscopy at the slit lamp or more formally with microperimetry.21,22
Effectiveness of Low Vision Rehabilitation Using Microperimetric Acoustic Biofeedback Training in Patients with Central Scotoma
Published in Current Eye Research, 2021
Esra Sahli, Deniz Altinbay, Pınar Bingol Kiziltunc, Aysun Idil
The PRL is identified by instrument and marked on the screen display. The instrument automatically calculates and displays fixation stability estimates relative to the PRL location. The fixation stability is quantified by the P1, P2 and Bivariate Contour Ellipse Area (BCEA) 95%, 63% values. P1 and P2 indicate the number of fixation points in percentage that are within the area of a circle with 1° and 2° diameter, respectively. Ninety-five percent BCEA and 63% BCEA values determine the ellipse area, expressed in square degrees, comprising 95% and 63% of the patient’s fixation points, respectively. Therefore, higher P1 and P2 values and lower 95% BCEA and 63% BCEA values indicate a better fixation capacity.11 The MAIA instrument also provides the information of the macular integrity assessment that compares the patients’ average macular threshold values and other variables with the age-adjusted averages for normal individuals. The analysis of residual average threshold decibel values classifies macular integrity index as normal (loss no larger than 40%); suspect (loss between 40% and 60%); and abnormal (loss greater than 60%).2 All the patients performed microperimetry in their first examination and follow-up exams. After evaluating the fixation stability level, it was determined whether the localization of existing PRL is suitable for reading; whether a new PRL could be created, and an appointment for training was arranged. Microperimetry was repeated before the first training.
Exploring microperimetry and autofluorescence endpoints for monitoring disease progression in PRPF31-associated retinopathy
Published in Ophthalmic Genetics, 2021
Danial Roshandel, Jennifer A. Thompson, Jason Charng, Dan Zhang, Enid Chelva, Sukanya Arunachalam, Mary S. Attia, Tina M. Lamey, Terri L. McLaren, John N. De Roach, David A. Mackey, Steve D. Wilton, Sue Fletcher, Samuel McLenachan, Fred K. Chen
Microperimetry was performed in 10 patients at baseline (Table S1). The large (10–2) test grid (central 20° field) was used in eight patients (mean [SD] age = 28 [12] years). The average (SD, range) MS and the number of scotoma were 10.1 (8.2, 0.0–22.9) dB and 60.8 (9.8, 43–68) loci, respectively. Six (75%) of the eight patients had dense scotoma noted on the 10–2 test; all aged >20 years. The 37 R test (central 6° field) was used in nine patients (mean [SD] age = 31 [11] years). The average (SD, range) microperimetry MS and the number of scotoma were 19.4 (6.8, 6.5–29.2) dB and 25.8 (13.8, 0–37) loci, respectively. Dense scotoma was found in only two of the nine patients (22%), both aged >40 years. Microperimetry MS was lower and the number of scotomatous loci was greater in older family members (Figure 2). Retinal sensitivity was <25 dB in all 10–2 test loci in all patients aged >30 years. The number of scotomatous loci ranged between 0 and 37 in 37 R grid and between 43 and 68 in 10–2 grid.
Peripapillary microperimetry for the diagnosis and follow-up of papilledema in cases treated for idiopathic intracranial hypertension
Published in Neurological Research, 2021
Gehad A. Elnahry, Amr M. Elemary, Nashwa Badr Eldin, Ashraf A. Nossair, Omar A. Barrada, Ayman G. Elnahry
Cases enrolled in the study were subjected to microperimetric measurements around the optic nerve head using Optos optical coherence tomography/scanning laser ophthalmoscopy imaging system (Optos, Scotland, UK). The following parameters were used: Stimulus size Goldman III, 4–2 strategy, peripapillary-14° pattern, duration of 200 ms, standardized peripapillary grid, and an eccentric cross of 1° as a fixation target. Twelve peripapillary microperimetric points were tested for each eye. Microperimetry was repeated after 1 month from the initiation of therapy (either medical or surgical). The following parameters were calculated for each patient at presentation and after 1 month of treatment and compared: The sum of the 12 peripapillary-tested points for the right and left eyes separately.The average of the sum of the 12 peripapillary-tested points for both eyes.The mean value for the 12 peripapillary-tested points for the right and left eyes separately.The mean value for the 24 peripapillary-tested points for both eyes.