Potential diagnostic dilemmas using the multifocal electroretinogram in intermittent exotropia

Evaluation of Structural and Functional Retinal Changes in Children With Intermittent Exotropia Versus Healthy Children

PURPOSE

To detect structural and functional changes in children with intermittent exotropia using optical coherence tomography, pattern electroretinography (ERG), and multifocal ERG.

METHODS

The study included 26 patients with intermittent exotropia and 26 healthy individuals matched for age and sex with a mean age of 9.23 and 11.20 years in the intermittent exotropia and control groups, respectively (P = .310). All patients underwent full ophthalmic examination including measurement of the angle of strabismus at near and far, and assessment of the macula and optic nerve using optical coherence tomography, pattern ERG, and multifocal ERG.

RESULTS

All patients had 6/6 best corrected visual acuity with no fixation preference. A significantly prolonged P and N wave latency was found in all measured rings of multifocal ERG of patients with intermittent exotropia, P wave amplitude was lower in rings 1 and 5, and N wave amplitude was lower in rings 1 and 2. Regarding pattern ERG, the amplitude of P50 wave was lower and N95 latency was prolonged in the intermittent exotropia group. The upper and lower ganglion cell complex and the superior retinal nerve fiber layer were significantly thinner in the intermittent exotropia group compared to controls.

CONCLUSIONS

Children with intermittent exotropia without any associated amblyopia or refractive error showed a subnormal pattern and multifocal ERG response in addition to a thinner ganglion cell layer and retinal nerve fiber layer compared to normal controls. This signifies that subtle structural and functional retinal changes are found in patients with intermittent exotropia. [J Pediatr Ophthalmol Strabismus. 2024;61(5):317-324.].

[Performance evaluation of multifocal electroretinography for monocular and binocular stimulation in anisochromoartiphakia]

Multifocal electroretinography (mfERG) helps evaluate the electrical potential of the retina in a set of points within 30 degrees. There is a significant number of factors affecting the value of mfERG data, which should be taken into account in research studies.

PURPOSE

To evaluate the difference and nature of changes in the amplitude (P1) and latency (P1, L1) parameters of mfERG in monocular (MS) and binocular stimulation (BS) in individuals with anisochromoartiphakia.

MATERIAL AND METHODS

The study included 24 patients aged 76.3±7.9 years with anisochromoartiphakia [one eye - IOL with yellow spectrum SN60AT (yIOL); the other is a transparent IOL - Rayacryl (trIOL)] comprising the main group, and 16 patients without artiphakia aged 51.6±4.6 years in the control group [one eye with the addition of a yellow light filter (YF) ZHS1 - a spectral analog of SN60AT, the other - without YF]. Recording of mfERG was done with MS and BS. Parameters under evaluation were DP1 (nV/deg²), amplitude P1 (mV) and latency LP1, LN1 (ms) in rings R1-R5.

RESULTS

In general, when switching from one ring to another under both types of stimulation and spectral correction, all indicators decrease. DP1 and P1 in MS and BS in the control group (49.2±17.7 and 53.6±17.5 nV/deg²) compared to the main group were higher (42.9±15.0 and 47.7±17.3 nV/deg²), LP1 and LN1 were shorter (41.2±5.0 and 44.8±4.3 ms in the control group, 44.0±4.1 and 50.7±21.1 ms in the main group). There was a significant difference between DP1R3 and DP1R4 in the control group (p≤0.003-0.050). In the control group without YF, P1R2 under MS was statistically significantly higher than under BS (p≤0.028). LP1 of R1, R3, R5 in the intergroup comparison was statistically significantly shorter in the control group without YF and MS (p≤0.033) and with YF in R1-R3, R5 (p≤0.003-0.023). LP1R2, LP1R4 were statistically significantly higher with trIOL in the main group under MS (p≤0.015; 0.047) and with yIOL in LP1R1, LP1R4, and LR5 (p≤0.053). The intergroup comparison showed that in the main group with yIOL, LP1R5 was statistically significantly lower under MS than BS (p≤0.032). When comparing LN1 between the groups, the statistically significant difference under MS without YF was observed in R5 (p≤0.002), while the difference under BS was insignificant. For YF, the increase in LN1 was statistically significant for MS in R2 and R3 (p≤0.010; 0.037) and for BS - in R1, R2 and R4 (p≤0.037; 0.003; 0.020). The intergroup comparison revealed that in the control group without YF, LN1R2 was statistically significantly lower under MS than BS (p≤0.028), and in the main group with trIOL, LN1R3 under MS was statistically significantly lower than under BS (p≤0.041).

CONCLUSION

In anisochromoartiphakia, spectral differences in the optical environment of the eye lead to changes in the parameters of mfERG in the form of a decrease in DP1 and elongation of LP1 and LN1 in comparison with healthy eye and non-spectral intraocular correction. MS or BS in mfERG does not have a significant impact on the character and value of these parameters. The use of a single-stage binocular recording of mfERG reduces the duration of the study, which is especially important when examining elderly patients.

The clinical applications of multifocal electroretinography: a systematic review

Multifocal electroretinography (mfERG) is an investigation that can simultaneously measure multiple electroretinographic responses at different retinal locations by cross-correlation techniques. mfERG therefore allows topographic mapping of retinal function in the central 40-50 degrees of the retina. The strength of mfERG lies in its ability to provide objective assessment of the central retinal function at different retinal areas within a short duration of time. Since the introduction of mfERG in 1992, mfERG has been applied in a large variety of clinical settings. This article reviews the clinical applications of mfERG based on the currently available evidence. mfERG has been found to be useful in the assessment of localized retinal dysfunction caused by various acquired or hereditary retinal disorders. The use of mfERG also enabled clinicians to objectively monitor the treatment outcomes as the changes in visual functions might not be reflected by subjective methods of assessment. By changing the stimulus, recording, and analysis parameters, investigation of specific retinal electrophysiological components can be performed topographically. Further developments and consolidations of these parameters will likely broaden the use of mfERG in the clinical setting.

Functional characterisation and serial imaging of abnormal fundus autofluorescence in patients with retinitis pigmentosa and normal visual acuity

AIM

To characterise and monitor abnormal fundus autofluorescence (AF) in patients with retinitis pigmentosa (RP) who have good visual acuity.

METHODS

21 patients with a clinical diagnosis of RP were examined. All had rod-cone dystrophy (ISCEV standard electroretinograms (ERGs)), visual acuity of 6/9 or better, and manifested a parafoveal ring of high density fundus AF. Repeat AF imaging was performed after periods of between 2 years and 5 years in 12 patients. Pattern ERG (PERG) and multifocal ERG (mfERG) were performed in 20 cases. Visual fields (VF), photopic and scotopic fine matrix mapping and small field PERGs were performed in representative cases.

RESULTS

The rings of high density AF varied in size between patients (from 4 degrees -16 degrees diameter). MfERGs showed relative preservation over the central macular area, correlating with the size of AF ring and with PERG and psychophysical data. Progressive constriction of the AF ring was demonstrated at follow up in three patients. Serial PERG, mfERG, and VFs, performed in one of these cases, showed evidence of deterioration concordant with ring constriction.

CONCLUSIONS

High density rings of AF, seen in some patients with RP with good visual acuity, demarcate areas of preserved central photopic function. MfERGs correlate with the area encircled by high density AF and the PERG data. The size of the ring of AF can show progressive constriction accompanied by increasing macular dysfunction.

Diabète et cytopathies mitochondriales : données anatomo-pathologiques

Maternal diabetes associated with neural deafness is designated as MIDD (maternal inherited diabetes and deafness); it is linked to a A3243G tRNA leucine gene mutation. The disease course is progressive and involvement of other systems is frequent. In most cases, macular pattern dystrophy is present. Muscular lesions are characteristic of mitochondrial myopathies. Mitochondrial abnormalities have also been observed in pancreas, heart, kidney, smooth muscle of the digestive tract with variable heteroplasmy levels. MIDD may present as a single syndrome or is part of MELAS or Kearns-Sayre syndrome.