Virtual Reality Hemifield Measurements for Corrective Surgery Eligibility in Ptosis Patients: A Pilot Clinical Trial

Abstract

Purpose: We developed an accelerated virtual reality (VR) suprathreshold hemifield perimetry algorithm, the median cut hemifield test (MCHT). This study examines the ability of the MCHT to determine ptosis severity and its reversibility with an artificial improvement by eyelid taping on an HTC Vive Pro Eye VR headset and the Humphrey visual field analyzer (HVFA) to assess the capabilities of emerging technologies in evaluating ptosis.

Methods: In a single visit, the MCHT was administered along with the HVFA 30-2 on ptotic untaped and taped eyelids in a randomized order. The primary end points were a superior field visibility comparison with severity of VF loss and VF improvement after taping for MCHT and HVFA. Secondary end points included evaluating patients' Likert-scaled survey responses on the comfort, speed, and overall experience with both testing modalities.

Results: VR's MCHT superior field degrees visible correlated well for severe category margin to reflex distance (r = 0.78) compared with HVFA's (r = -0.21). The MCHT also demonstrated noninferiority (83.3% agreement; P = 1) against HVFA for detection of 30% or more superior visual field improvement after taping, warranting a corrective surgical intervention. In comparing hemi-VF in untaped eyes, both tests demonstrated relative obstruction to the field when comparing normal controls to severe ptosis (HVFA P < 0.05; MCHT P < 0.001), which proved sufficient to demonstrate percent improvement with taping. The secondary end point of patient satisfaction favored VR vision testing presentation mode in terms of comfort (P < 0.01), speed (P < 0.001), and overall experience (P < 0.01).

Conclusions: This pilot trial supports the use of MCHT for the quantitative measurement of visual field loss owing to ptosis and the reversibility of ptosis that is tested when conducting a presurgical evaluation. We believe the adoption of MCHT testing in oculoplastic clinics could decrease patient burden and accelerate time to corrective treatment.

Translational relevance: In this study, we look at vision field outputs in patients with ptosis to evaluate its severity and improvement with eyelid taping on a low-profile VR-based technology and compare it with HVFA. Our results demonstrate that alternative, portable technologies such as VR can be used to grade the degree of ptosis and determine whether ptosis surgery could provide a significant superior visual field improvement of 30% or more, all while ensuring a more comfortable experience and faster testing time.

Figure 1.

Flow diagram of data selection process for uncorrected and corrected visual field testing in ptosis patient population. FL of 50 or more, false-positive (FP) rate of 15 or greater. *Inferior fields were obtained in patients with eyelid droop below the horizontal meridian.

Figure 2.

Flow diagram depicting randomly assigned sequences A and B for the minimalization of technology-specific confounding variables.

Figure 3.

(Left) HVFA 30-2 visual field output with a yellow meridian tracing of visible SVF. (Right) SVF algorithm VR output after median cut algorithm processing to approximate the AUM.

Figure 4.

Schematic of the determination of y-axis degrees and prediction method for MRD1 measurements in patients with ptosis. The measurement of the meridian at less than 10 Apostilibs on the Humphrey grayscale map was predicted to correlate with the MRD1 measurements.

Figure 5.

Correlations between percent visible field and percent degrees visible for VR and HVFA. The percent degree visible was determined by dividing the degrees seen at x = 0 by the maximum possible visible degrees seen in the test (N = 30). Given the overlap in values, the number of points varies between the two graphs with 14 points overlapping on the left graph and 8 points on the right graph. Consistent statistically significant positive correlations between the percent degrees visible and percent visible field provides confidence in the association between the two independent measurements.

Figure 6.

Fractional analysis of HVFA and VR for mild to severe ptosis (MRD1 of ≤2) with a sample size of 24. Both the right and left graphs have a 7-point overlap. The left demonstrates HVFA percent degrees visible versus MRD1 scores divided by severe (MRD1 of <2 mm) versus mild ptosis (MRD1 of ≥2 mm). The HVFA had weak negative correlations for both the severe and mild ptosis groups (r = −0.21 and −0.48, respectively, both of which were not significant). The right demonstrates VR percent degrees visible versus MRD1 scores divided by severe (MRD1 of <2 mm) versus mild ptosis (MRD1 of ≥2 mm). The VR had significantly strong positive correlations between percent degrees visible and MRD1 for severe ptosis patients (r = 0.78; P = 0.00013), but poor positive, not statistically significant correlations for mild ptosis (r = 0.015; P = 0.98), demonstrating that VR has stronger associations between percent degrees visible versus MRD1 scores.

Figure 7.

(A) Percent visible field AUMs mapped as scatter plots of HVFA and VR tests with an MRD heat map. (B) Dotted diagonal lines with data points on the line indicating a perfect agreement between two tests, points above the dotted line have lower VR than HVFA percent visible AUM and points below the dotted line have higher VR percent visible AUM than HVFA. Each data point represents a percent visible AUM value from one eye. (C) Scatter plot of each AUM classified by severity. (D) Averaged percent visible AUM values for HVFA and VR tests.

Figure 8.

Matrix demonstrating agreement between VR and HVFA in a 30% or greater AUM increase with taping of the eyelid. The matrix cells contain the number of eyes that fell into each respective category.

Figure 9.

Likert graphs demonstrating patients’ ratings of HVFA and VR parameters based on survey data obtained after participants finished both HVFA and VR examinations focusing on three principal characteristics of the tests: speed, comfort, and overall experience. The VR examinations consistently scored higher (higher = better) compared with the HFVA for all three characteristics.

Figure 10.

Average test times for the HVFA versus MCHT (VR) demonstrates the VR tests are significantly shorter than the Humphrey, averaging 91.2 seconds compared with the Humphrey averaging 421.5 seconds per eye.