Pediatric Perimeter-A Novel Device to Measure Visual Fields in Infants and Patients with Special Needs

The diagnostic accuracy and feasibility of paediatric visual field tests: A systematic review

PURPOSE

Alternative non-standard paediatric visual field (VF) tests have been developed to address the challenges associated with standard approaches. However, diagnostic accuracy of these new VF tests has not yet been rigorously evaluated. This systematic review aims to explore diagnostic accuracy and feasibility of non-standard VF tests in paediatric patients.

METHODS

The following databases were searched for English language studies comparing a non-standard paediatric VF test to standard methods, such as standard automated perimetry (SAP), manual kinetic perimetry (MKP) and confrontation testing (CT): EMBASE, PubMed, Ovid MEDLINE, Web of Science, Scopus, VisionCite, Cochrane Library, ClinicalTrials.gov, African Index Medicus, LILACS, Trip and grey literature databases. Studies included were of children ≤18 years old with suspected or known VF defects (n > 3). Case reports, case series, editorials and letters were excluded. This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

RESULTS

Thirty studies (n = 2074 children, age range: 2 months to 18 years) published between 1990 and 2023 met the inclusion/exclusion criteria. Twenty index tests were reported, sorted into four categories of methods: behavioural/observational (5), electrophysiological (2), modifications of standard perimetry (11) and eye tracking (2). Risk of bias, based on the QUADAS-2 results, was unclear or high for most studies. Sensitivities of 10 studies (behavioural/observational [2]; electrophysiological [2]; modifications of standard perimetry [2] and eye tracking [4]) were 60%-100%, 75%, 80%-94% and 70%-100%, and specificities were 98%-100%, 86%-88%, 68%-100% and 50%-100%, respectively.

CONCLUSIONS

Alternative non-standard paediatric VF tests, and behavioural/observational methods in particular, show potential for adequate diagnostic accuracy and feasibility, although limited to certain conditions and ages. Studies with complete reporting and low risk of bias are needed to determine the diagnostic accuracy and feasibility of non-standard paediatric VF tests.

Alternative perimetric tests for patients with drug-resistant epilepsy

OBJECTIVE

Visual field assessment is an important presurgical test for patients with drug-resistant epilepsy (DRE), particularly with posterior cortex epilepsy. However, the assessment using conventional perimeters like Humphrey Visual Field Analyzer (HFA) may not always be feasible in some patients. This study aims to determine if alternative methods like tangent screen perimetry or Baby Vision Screener (BaViS) can be used for such patients.

METHODS

This retrospective study included 17 patients (mean age: 18 ±  8.7, range: 6 to 38 years) with DRE. Visual fields were attempted first with HFA and then with one or both alternative methods, by different examiners. Visual field extent was measured using the kinetic perimetry mode in the alternative methods. With HFA, kinetic and/or static perimetry was attempted.

RESULTS

Only 12% of the patients were able to perform the HFA. Whereas the testability of BaViS was 91% and tangent screen perimetry was 87%. Comparable visual field isopters were obtained on one patient on whom all the 3 tests could be performed, and in two patients on whom at least two tests could be performed reliably. For one patient, visual field isopters could not be quantified on any device. In this patient, a gross visual field assessment was possible using BaViS.

CONCLUSION

BaViS or tangent screen perimeter can be used to quantify visual field defects in patients with DRE when conventional perimetry is not possible. Such an approach may help the clinician in assessing the suitability of patients with DRE and visual field deficits, for epilepsy surgery.

Current perspective: Cerebral visual impairment-The impending doom

Cerebral visual impairment (CVI) has emerged as an important cause of morbidity in young children. CVI children often have a large number of visual symptoms along with motor abnormalities. It is the need of the hour to build an integrated approach towards their management. This article aimed to provide a comprehensive view of the manifestations, evaluation, and management of children with CVI.

Evaluation of Virtual Reality Perimetry and Standard Automated Perimetry in Normal Children

Purpose

The Olleyes VisuALL-K is a pediatric videogame-based static threshold perimeter using a virtual reality headset. We determined normal threshold sensitivities for the 24-2 test locations using the virtual reality perimetry (VRP) and also tested patients on the Humphrey Field Analyzer (HFA). Patient satisfaction for the two instruments was compared.

Methods

This exploratory study tested 50 normal pediatric participants aged 8 to 17 years on the HFA and VRP. The main outcome measure was threshold sensitivity at the 24-2 test locations for the two instruments.

Results

The mean participant age was 13.0 ± 2.6 years; 50% were female. The threshold values for VRP are reported as measured on the device and after conversion to an HFA-equivalent scale. Age-adjusted thresholds showed a mean sensitivity of 31.8 ± 1.1 dB (46.1 ± dB HFA equivalent) diminution from the maximum light intensity in the VRP and 31.0 ± 1.5 dB diminution from the maximum light intensity in the HFA; interparticipant variability in mean threshold sensitivity was 2.7 ± 0.4 dB for the VRP and 2.7 ± 0.6 dB for the HFA. The HFA demonstrated decreased threshold sensitivity with increasing eccentricity, whereas the VRP threshold did not seem to vary with eccentricity. Mild age effects on threshold sensitivity were seen in the VRP and the HFA (R2 = 0.11, P < 0.001 and R2 = 0.05, P < 0.05, respectively). The mean time to completion for VRP and HFA was 7.6 ± 1.5 and 5.3 ± 0.9 min/eye, respectively (P < 0.0001). Patient satisfaction scores favored VRP (P < 0.01) despite the longer test duration.

Conclusions

The Olleyes game-based VRP and HFA can be used to map out the peripheral vision in normal children. The VRP has a higher patient satisfaction when used in children than the HFA. The portability of the test allows it to be performed in a myriad of environments, lending a flexibility that can benefit this population.

Translational Relevance

This virtual reality perimetry device provides an alternative to the Humphrey Field Analyzer for children.

Quantification of gaze reaction time in infants with Pediatric Perimeter

Purpose

We quantified the eye/head (gaze) reaction time in infants to establish a normative database for the Pediatric Perimeter device. Additionally, we tested the hypothesis that gaze reaction time will reduce with age.

Methods

A cross-sectional study was conducted. Healthy infants between 3 to 10 months of age were recruited. Peripheral visual field stimuli (hemifield and quadrant stimuli) were presented in the Pediatric Perimeter device. Infant’s gaze to these stimuli was observed, documented in real time, and video recorded for offline analysis.

Results

A total of 121 infants were tested in three age group bins [3–5 months, n = 44; >5–7 months, n = 30 and >7–10 months, n = 47]. Overall, 3–5 months old had longer reaction time when compared to the older infants particularly for stimuli presented in the quadrants (Kruskal-Wallis, p<0.038). A significantly asymmetric difference (p = 0.025) in reaction time was observed between the upper (median = 820ms, IQR = 659-1093ms) and lower quadrants (median = 601ms, IQR = 540-1052ms) only for the 3–5 months old infants.

Conclusion

This study provides the normative gaze reaction time of healthy infants. With increase in age, there is reduction in reaction time and disappearance of reaction time asymmetry in quadrant stimuli. The longer reaction time for upward gaze could be due to delayed maturation of neural mechanisms and/or decreased visual attention.

The Assessment of Visual Fields in Infants Using Saccadic Vector Optokinetic Perimetry (SVOP): A Feasibility Study

Purpose

To examine the feasibility of saccadic vector optokinetic perimetry (SVOP), an automated eye tracking perimeter, as a tool for visual field (VF) assessment in infants.

Methods

Thirteen healthy infants aged between 3.5 and 12.0 months were tested binocularly using an adapted SVOP protocol. SVOP uses eye tracking technology to measure gaze responses to stimuli presented on a computer screen. Modifications of SVOP for testing infants included adjusting the fixation target to display a short animation, increasing the stimulus size to equivalent to Goldmann V, and introducing a tiered test pattern strategy. Binocular, single-quadrant confrontation VF testing and Keeler preferential looking cards visual acuity testing was also performed.

Results

Using multiple test attempts when required, all but the youngest infant (12 of 13 [92.3%]) successfully completed a 4-point screening test. Seven infants (53.8%) successfully completed the 12-point test, four (30.8%) successfully completed the 20-point test, and three (23.1%) successfully completed the 40-point test. The effect of multiple test attempts and the complexity of the test pattern (number of test points) on performance was investigated, including test completion rate, percentage of correctly seen stimuli, and average time per tested stimulus.

Conclusions

The modified SVOP test strategy allowed successful assessment of binocular VFs in healthy infants. Future data collection from larger cohorts of infants is needed to derive normative limits of detection and assess accuracy in detecting and monitoring infant VF abnormalities.

Translational Relevance

Eye tracking perimetry may provide a useful method of automated VF assessment in infants.

Uncovering homonymous visual field defects in candidates for pediatric epilepsy surgery

OBJECTIVES

Perimetry in children can be challenging due to low cooperation and short attention span. Especially during the pre-surgical work-up of children with pharmaco-refractory epilepsies, however, diagnosing homonymous visual field defects (HVFDs) can be crucial for planning surgical strategies. Here, we evaluated "campimetry" for visual field testing in children. Furthermore, we analyzed strabismus and anomalous head posture as clinical signs for HVFDs.

METHODS

Campimetry and a standard orthoptic examination were performed in 18 patients (age range: 3 y 2 m-18 y) who underwent epilepsy surgeries in our center during the study period, and in 11 additional patients (age range: 2 y 10 m-22 y 10 m) with suspected or confirmed HVFDs.

RESULTS

In 16/18 patients of our unselected surgery cohort, pre- and postoperative campimetry was successfully completed. Of these, only 7/16 patients had intact visual fields pre- and postoperatively, while 5/16 patients already showed preoperative HVFDs and 4/16 patients suffered newly acquired HVFDs as calculated consequences of the surgery. Regarding clinical signs, strabismus (mostly esotropia) and anomalous head posture were specific indicators of HVFDs (strabismus: 6/12 with HVFDs vs 1/18 without; anomalous head posture: 8/12 with HVFDs vs 0/18 without).

CONCLUSIONS

For perimetry in children with limited cooperation, we suggest campimetry as it allows early detection and fast delineation of HVFDs. This is particularly important in pediatric epilepsy surgery patients, who display a surprisingly high proportion of HVFDs (9/16). Both, strabismus and anomalous head posture can indicate such HVFDs. Therefore, clinicians should pay attention to these clinical signs, especially in the context of epilepsy surgery.

Visual function in children with primary brain tumors

PURPOSE OF REVIEW

To review the recent advances in understanding how primary brain tumors affect vision in children.

RECENT FINDINGS

Children with primary brain tumors may have vision loss due to involvement of their afferent visual pathways or from papilledema. These vision deficits may go unrecognized until later in life, years after treatment of the primary lesion. Strabismus and cranial nerve palsies may occur as a result of brain tumors. Ophthalmologists can monitor and treat young children at risk for vision loss from amblyopia as a result of effects from their underlying lesion. Advances in imaging techniques have made it possible to quantify damage to the visual pathways with objective tests.

SUMMARY

Systematic referrals for evaluation by an ophthalmologist should occur early in the course of treatment of primary brain tumors as these evaluations may improve visual outcomes and quality of life.

Effect of Age, Sex, Stimulus Intensity, and Eccentricity on Saccadic Reaction Time in Eye Movement Perimetry

Purpose

In eye movement perimetry (EMP), the extent of the visual field is tested by assessing the saccades using an eye tracker. The aim of the present study was to determine the effects of age and sex of the subjects, the eccentricity and intensity of the peripheral stimuli on saccadic reaction time (SRT), and the interaction between these parameters in healthy participants.

Methods

Healthy participants aged between 20 to 70 years underwent a complete ophthalmic examination and an EMP test. SRT was determined from detected peripheral stimuli of four intensity levels. A multilevel mixed-model analysis was used to verify the influence of subject and stimulus characteristics on SRT within the tested visual field.

Results

Ninety-five subjects (mean age 43.0 [15.0] years) were included. Age, stimulus intensity, and eccentricity had a statistically significant effect on SRT, not sex. SRTs were significantly faster with increasing stimulus intensity and decreasing eccentricity (P < 0.001). At the lowest stimulus intensity of 192 cd/m², a significant interaction was found between age and eccentricity.

Conclusions

The current study demonstrated significant SRT dependence across the visual field measured up to 27°, irrespective of sex. The presented SRT values may serve as a first normative guide for EMP.

Translational Relevance

This report of SRT interaction can aid in refining its use as a measure of visual field responsiveness.

Visual function assessment, ocular examination, and intervention in children with developmental delay: A systematic approach. Part 1

Children with special needs form a unique subset with regards to visual function and examination techniques needed to assess them. With more awareness among the general public, neurologists, and pediatricians, these children are referred for assessment to the ophthalmologist or optometrist and sometimes even to the rehabilitation professional at an early age. This clinical practice guideline and review gives a systematic approach for examining the visual functions of a child with special needs. It outlines the procedures to be followed with equipment needed in clinical practice. Functional vision assessment guidelines are also included. This is the first part in a two-part series, with the first part presenting clinical examination guidelines and the second presenting intervention and vision enhancement techniques.