Longitudinal Study of Visual Discomfort Symptoms in College Students

Visual discomfort and contact lens wear: A review

The purpose of this manuscript is to describe how vision influences contact lens discomfort and review the evidence supporting the hypothesis that contact lens discomfort can be caused by vision and vision-related disorders. Contact lens discomfort is a misunderstood and difficult to manage clinical condition. Most treatments and strategies aimed at alleviating discomfort focus on optimizing the contact lens fit and its relationship with the ocular surface, but these strategies commonly fail at relieving discomfort symptoms. Many vision and vision-related disorders share symptoms with those reported by uncomfortable contact lens wearers. This paper will review evidence and literature that describes how these vision and vision-related disorders may influence comfort in contact lens wearers. Acknowledging how vision influences contact lens discomfort will improve future research intended to better understand the condition, allow for more effective clinical management, and reduce rates of discontinuation.

Translation and validation of convergence insufficiency symptom survey to Italian: Psychometric results

PURPOSE

This study aimed to translate the Convergence Insufficiency Symptom Survey (CISS) into the Italian language and assess psychometric properties of the translated questionnaire (CISS_I).

METHODS

The CISS_I was arranged according to guidelines for a comprehensive multistep methodologic process for translating, adapting, and validating psychometric instruments in health care research. The CISS_I questionnaire was administered to 103 volunteers (21.8 ± 2.2 years), students in higher education, at two different times. A complete optometric evaluation was performed including subjective refraction, best corrected visual acuity, near point of convergence, prism fusional ranges to blur, diplopia and recovery, TNO stereo test and prism cover test for measurement of heterophoria.

RESULTS

The performance of the CISS_I in terms of validity showed some points of weakness. Sensitivity was 42%, specificity was 74%, positive predictive value was 27% and negative predictive value was 85%. The area under the ROC curve was 0.672. On the contrary, the results showed good internal consistency of the CISS_I (Cronbach's alpha - α=0.89) and good test-retest reliability (ICC = 0.92). Rasch analysis showed good model fit (all items, except one, with infit and outfit mean square between 0.7 and 1.3), good measurement precision (person separation = 2.66) and good targeting -0,81 logits but also some evidence of multidimensionality.

CONCLUSIONS

The CISS_I showed some point of weakness in terms of validity but also good psychometric properties and has been shown to be applicable to an Italian speaking population to quantify the visual discomfort associated with near vision in higher education students. The results show that high CISS_I score is not necessarily linked to convergence insufficiency, while low scores can exclude the presence of this anomaly. The CISS_I can help in interpreting and monitoring convergence insufficiency symptoms in already identified subjects, but it is not suitable for screening a general population of young adults.

Visual Sensitivity in Complex Regional Pain Syndrome and Fibromyalgia: An Online Study

Perceptual anomalies can provide insights into underlying pathologies even when they are not the main symptom of many clinical conditions. Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions associated with changes in the central nervous system, possibly leading to enhanced visual sensitivity. It is unclear whether this occurs more than for people with other types of pain. We examined visual sensitivity elicited by different stimuli and in daily life, through an online study of people with CRPS (n = 57), fibromyalgia (n = 74), other pain (n = 50), and no pain (n = 89). Respondents rated changes in pain, discomfort, or distress from viewing patterns with different spatial frequencies (lower-order visual processing), and reversible figures (bistable images; higher-order visual processing). We assessed visual sensitivity in daily life using the Leiden Visual Sensitivity Scale and Visual Discomfort Scale. Respondents with CRPS or fibromyalgia reported more visual discomfort than pain-related and pain-free controls while viewing striped patterns and a circle, with no effect of spatial frequency. They reported more pain while viewing a nonreversible square, but not reversible figures (Necker Cube, Duck/Rabbit). Finally, they reported more daily visual sensitivity than pain-related and pain-free controls. Suppressing visual cortical activity might benefit people with CRPS or fibromyalgia.

Validation of the Leiden Visual Sensitivity Scale and Visual Discomfort Scale in Chronic Pain Conditions

Discomfort provoked by normally innocuous visual stimuli has been reported by people with chronic pain. Visual discomfort may be higher in pain conditions in which central sensitization is implicated, such as Complex Regional Pain Syndrome (CRPS) and fibromyalgia. In an online study, we validated the Leiden Visual Sensitivity Scale (L-VISS) and Visual Discomfort Scale (VDS) in people with CRPS (n = 57), fibromyalgia (n = 75), and general chronic pain (n = 53); investigated whether these groups and pain-free controls (n = 125) differed in visual discomfort; and evaluated the effect of age. The L-VISS and VDS had good internal consistency. Both scales were positively related with experimentally induced visual distortions for mid-spatial frequency striped patterns, suggesting good construct validity. The scales were positively related with each other, and dissociated between the pain and pain-free groups in similar ways, suggesting good construct validity. There was no relationship between age and L-VISS scores and a small negative relationship between age and VDS scores. Visual discomfort was highest in the fibromyalgia group, followed by the CRPS group. This research confirms the utility of the L-VISS and VDS for measuring visual sensitivity in chronic pain and adds to evidence that central sensitization is an important mechanism of visual discomfort.

Ocular symptoms associated with digital device use in contact lens and non-contact lens groups

PURPOSE

Previous reports indicate that "eye fatigue" occurs in roughly 60 % of the adult population using digital devices and may negatively impact quality of life. However, the construct of eye fatigue remains poorly understood. The goal of this study was to quantify the relationship among symptoms most frequently associated with eye fatigue in those using digital devices.

METHODS

Six hundred and two soft contact lens (SCL) wearers and 127 non-contact lens (non-CL) wearers who reported using digital devices at least 4 hours per day completed a questionnaire assessing the frequency and severity of ten symptoms commonly associated with digital device-related eye fatigue. Subjective ratings were made separately for each symptom using unipolar, five-point Likert scales.

RESULTS

From the initial pool of respondents, 89 % of the SCL wearers reported experiencing eye fatigue more than once per month, while over 60 % reported more than once per week. Notably, eye fatigue frequency did not differ between the soft contact and non-contact lens groups. Although eye strain/pain, dryness, and tired eyes were the most frequently endorsed symptoms by both groups, only dryness and eye irritation were significant factors that discriminated the SCL from the non-CL wearers on the basis of frequency and severity. Principal component analysis indicated that eye strain/pain, soreness, tired eyes, and headaches may comprise a "primary sensations" factor, whereas burning, eye irritation, tearing and dryness comprise a "secondary or surface sensations" factor, and blurred/double vision and words move/float comprise a "visual sensations" factor. Confirmatory factor analysis (CFA) of frequency and severity ratings for SCL wearers yielded excellent fits (RMSEA = 0.046 and 0.050, respectively) with construct reliabilities ranging from 0.729 to 0.824.

CONCLUSION

Frequent and severe eye fatigue is highly prevalent among both soft contact lens and non-contact lens wearers. Those utilizing SCL do not experience symptoms at higher frequency or severity. Key descriptors of digital eye fatigue have been identified and may then be used to help identify and evaluate specific causative, palliative, or ameliorating factors.

Factor structure of the convergence insufficiency symptom survey questionnaire

The purpose of this study is to analyze the factorial structure of the Convergence Insufficiency Symptom Survey questionnaire with 15 items, in order to identify latent dimensions that can contribute to a more focused implementation. The questionnaire was self-administered in paper by 183 university students, in the age span of 18 to 30. Both Kaiser-Meyer-Olkin measure and Bartlett's sphericity test were performed to ensure the validity of the factorization. In order to analyze the principal components, factors which obtained eigenvalues greater than 1 were chosen. The extraction of factors was performed after computing a Promax rotation and a Kaiser criterion. In each extracted factor, the internal consistency was used to prove its reliability. Bartlett's sphericity test was statistically significant (p <0.001), and the Both Kaiser-Meyer-Olkin test was 0.89, confirming the factorization of this instrument. Exploratory factor analysis followed by a Promax rotation and scree plots graphic, extracted three factors that explained 62.1% of the total variance. The composition of each factor suggests the following meanings: Factor 1 (somatic sensation) includes 8 of 15 items; Factor 2 (impaired vision) includes 3 of 15 items; Factor 3 (cognitive performance) includes 4 of 15 items. Cronbach's alpha coefficient demonstrated good internal consistency (α> 0.75) in three dimensions. The multivariate statistical analysis of the Convergence Insufficiency Symptom Survey revealed a three-factor structure, so new forms of questionnaire analysis can be designed in order to obtain gains in the management of a symptomatic patient, using 3 subscores, one for each factor, instead of a total score. The factorial structure of the questionnaire can be used with a high level of confidence in future investigations, which aim to assess which dimensions are most affected in each type of visual changes and develop more targeted therapeutic performances.

Accommodation changes after visian implantable collamer lens with central hole for high myopia: A STROBE-compliant article

To characterize the accommodative changes in high-myopic patients after the implantation of the Visian implantable collamer lens with a central hole (ICL V4c).This prospective study enrolled 30 patients (60 eyes) with uneventful surgery of ICL V4c implantation. Parameters including amplitude of accommodation (AA), monocular and binocular facility of accommodation (FA), positive relative accommodation (PRA), negative relative accommodation (NRA), near point convergence (NPC), accommodative response, and accommodation convergence/accommodation (AC/A) ratio were assessed before surgery, at 1 and 3 months postoperatively.Mean preoperative SE was -10.86 ± 3.87 diopter (D) (range, -6.5D to -22D), which improved to 0.27 ± 0.51D at 1 month and 0.09 ± 0.47D at 3 months after surgery (P <.001). Significant improvements in AA, NRA, PRA, NPC, monocular, and binocular FA were seen at 1 month and 3 months postoperatively compared to the values before surgery (P <.05), but the difference between 1 month and 3 months were not obvious (P >.05) except for binocular FA (P = .002). However, no significant changes were seen in either AC/A ratio or accommodative response at any postoperative follow-ups in contrast to those before surgery (P >.05). Similar changes in accommodative function were found in patients with less myopia (> -10.00D) and those with more myopia (≤10.00D) (P >.05).The accommodative function of eyes after the implantation of ICL V4c is enhanced and stabilizes at 1 month, except for the AC/A ratio and accommodative response. The clearer vision and increased amount of accommodation for near target account for the majority of the improvement.

Fruit and vegetable consumption and its relation to risk of asthenopia among Chinese college students

AIM

To investigate the associations between fruit and vegetable consumption and risk of asthenopia among Chinese college students.

METHODS

A total of 1022 students were selected from five universities by a multi-stage stratified cluster sampling method. They were surveyed via a self-administered questionnaire including socio-demographic features, dietary and lifestyle habits, eye-related symptoms, eye care habits and history of diseases. Ascertainment of asthenopia was based on participants' subjectively reported symptoms. The associations between fruit and vegetable intake with asthenopia risk were assessed using multivariate logistic regression analysis.

RESULTS

There were no significant associations between total fruit and vegetable, total vegetable, or fruit and the risk of asthenopia. Higher intake of dark-green leafy vegetable was likely to be inversely associated with asthenopia risk [odd ratio (OR): 0.60; 95%CI: 0.37-0.97; P_trend=0.21] after controlling for nondietary and dietary risk factors. Stratified analysis showed that the inverse association between dark-green leafy vegetable intake and asthenopia risk was limited to participants with suboptimal eyesight (OR: 0.45; 95%CI: 0.25-0.82; P_trend=0.05), wearing glasses (OR: 0.35; 95%CI: 0.17-0.72; P_trend=0.03) or using computer ≥3h/d (OR: 0.48; 95%CI: 0.25-0.93; P_trend=0.08).

CONCLUSION

A higher consumption of dark-green leafy vegetable is associated with a lower asthenopia risk among college students with suboptimal eyesight and poor eye care habits.

Development of the Japanese version of the Visual Discomfort Scale

BACKGROUND

Visual stimuli, such as stripes and texts, can induce "visual discomfort" including perceptual and somatic symptoms. Individuals reporting high levels of visual discomfort might experience migraine headache and may have reduced reading efficiency due to visual perceptual difficulties. This study aimed to develop and validate the Japanese version of the Visual Discomfort Scale, which measures proneness to visual discomfort.

METHODS AND RESULTS

In Survey 1, 428 adults completed the Japanese version and a questionnaire assessing migraine morbidity. Rasch analysis revealed that the Japanese version is a unidimensional scale with a high amount of unexplained variance due to random noise rather than another dimension, and has high person and item reliabilities. Participants with migraine exhibited high scores in the Japanese version, indicating the construct validity of the scale. Survey 2 with 118 adults revealed a strong test-retest correlation for the Japanese version, indicating the stability of the scale.

CONCLUSION

The Japanese version of the Visual Discomfort Scale is a sufficiently reliable and valid scale for assessing visual discomfort, although its unidimensionality leaves room for further improvements.

Accommodative changes after SMILE for moderate to high myopia correction

Background

To investigate accommodative response and accommodative lag changes after femtosecond laser small incision lenticule extraction (SMILE) for moderate to high myopia correction.

Methods

A total of 32 eyes of 32 patients with no strabismus who underwent SMILE were enrolled in this prospective clinical study. The accommodative response was obtained viewing monocularly with spherical equivalent refractive error corrected, using an open-field autorefractor at different stimulus levels (2.00D, 2.50D, 3.00D, 4.00D and 5.00D) for the right eye before a standard SMILE surgery and at 1-month follow-up after surgery.

Results

The mean age of the patients were 23.34 ± 2.90 years and the mean preoperative manifest refraction spherical equivalent was −5.74 ± 1.98 diopters. Significant differences were detected in both preoperative and postoperative accommodative responses to different stimulus levels (P < 0.001). Multiple linear regression model analysis revealed preoperative manifest refractive spherical equivalent (P = 0.006) and preoperative accommodative lag (P = 0.04) showed a significant impact on postoperative accommodative lag.

Conclusions

This is the first report of accommodative changes after SMILE. Our preliminary results showed that a decrease in postoperative accommodative lag that might be related to the relief of the visual discomfort symptom.

Evaluation of visual stress symptoms in age-matched dyslexic, Meares-Irlen syndrome and normal adults

AIM

To examine the prevalence of dyslexia and Meares-Irlen syndrome (MIS) among female students and determine their level of visual stress in comparison with normal subjects.

METHODS

A random sample of 450 female medical students of King Saud University Riyadh (age range, 18-30y) responded to a wide range of questions designed to accomplish the aims of this study. The detailed questionnaire consisted of 54 questions with 12 questions enquiring on ocular history and demography of participants while 42 questions were on visual symptoms. Items were categorized into critical and non-critical questions (CQ and NCQ) and were rated on four point Likert scale. Based on the responses obtained, the subjects were grouped into normal (control), dyslexic with or without MIS (Group 1) and subjects with MIS only (Group 2). Responses were analysed as averages and mean scores were calculated and compared between groups using one way analysis of variance to evaluate total visual stress score (TVSS=NCQ+CQ), critical and non-critical visual stress scores. The relationship between categorical variables such as age, handedness and condition were assessed with Chi-square test.

RESULTS

The completion rate was 97.6% and majority of the respondents (92%) were normal readers, 2% dyslexic and 6% had MIS. They were age-matched. More than half of the participants had visited an eye care practitioner in the last 2y. About 13% were recommended eye exercises and one participant experienced pattern glare. Hand preference was not associated with any condition but Group 1 subjects (3/9, 33%) were significantly more likely to be diagnosed of lazy eye than Group 2 (2/27, 7%) and control (27/414, 7%) subjects. The mean±SD of TVSS responses were 63±14 and it was 44±9 for CQ and 19±5 for NCQ. Responses from all three variables were normally distributed but the CQ responses were on the average more positive (82%) in Group 2 and less positive (46%) in Group 1 than control. With NCQ, the responses were equally less positive in Group 1 and 2 than control. Group 2 subjects showed significantly higher TVSS (P=0.002), NCQ (P=0.006) and CQ (P=0.008) visual stress scores than control but no difference between Group 1 and control subjects, was observed for all scores (P>0.05, for all comparisons).

CONCLUSION

The prevalence of dyslexia and MIS among Saudi female students was 2% and 6%, respectively. Critical questions performed best for assessing visual stress symptoms in dyslexic and MIS subjects. Generally, students with MIS were more sensitive to visual stress than normal students but dyslexics were more likely to present with a lazy eye than MIS and normal readers.

Accommodative and binocular dysfunctions: prevalence in a randomised sample of university students

BACKGROUND

The aim was to analyse the prevalence of symptomatic accommodative and non-strabismic binocular dysfunctions in a randomised population of university subjects.

METHODS

A cross-sectional study was conducted with a randomised sample of 175 university students aged between 18 and 35 years. All subjects were given a visual examination in which their symptoms were recorded, as well as performing objective and subjective refractive examinations and accommodative and binocular tests. Each subject was tested for the presence of uncorrected refractive error. Accommodative dysfunctions (AD) and binocular dysfunctions (BD) were diagnosed according to the number of clinical signs associated with each disorder, considering the signs that could be associated with each dysfunction as fundamental or complementary. An accommodative or binocular dysfunction was diagnosed when the subjects met two conditions: presenting with any kind of visual symptom in their clinical history and presenting the fundamental sign associated with each dysfunction as well as two or more complementary signs. Those subjects who presented with only an uncorrected refractive error were considered within the group called refractive dysfunction (RD).

RESULTS

The overall prevalence of accommodative and/or binocular dysfunctions was 13.15 per cent and for refractive dysfunction it was 45.14 per cent. Accommodative dysfunctions were present in 2.29 per cent of the population, binocular dysfunctions were observed in eight per cent and accommodative dysfunctions together were found in 2.86 per cent of the university students. Within the accommodative and binocular disorders, the most prevalent dysfunctions were convergence insufficiency, with a prevalence of 3.43 per cent and convergence excess and accommodation excess, both with a prevalence of 2.29 per cent.

CONCLUSION

Binocular dysfunctions were more prevalent than accommodative dysfunctions or accommodative and binocular dysfunctions together in a randomised population of university students.

Characterization of Visual Symptomatology Associated with Refractive, Accommodative, and Binocular Anomalies

Purpose. To characterize the symptomatology of refractive, accommodative, and nonstrabismic binocular dysfunctions and to assess the association between dysfunctions and symptoms. Methods. 175 randomised university students were examined. Subjects were given a subjective visual examination with accommodative and binocular tests, evaluating their symptomatology. Accommodative and binocular dysfunctions (AD, BD) were diagnosed according to the number of existing clinical signs: suspect AD or BD (one fundamental clinical sign), high suspect (one fundamental + 1 complementary clinical sign), and definite (one fundamental + 2 or more complementary clinical signs). A logistic regression was conducted in order to determine whether there was an association between dysfunctions and symptoms. Results. 78 subjects (44.6%) reported any kind of symptoms which were grouped into 18 categories, with “visual fatigue” being the most frequent (20% of the overall complaints). Logistic regression adjusted by the presence of an uncorrected refractive error showed no association between any grade of AD and symptoms. Subjects with BD had more likelihood of having symptoms than without dysfunction group (OR = 3.35), being greater when only definite BD were considered (OR = 8.79). Conclusions. An uncorrected refractive error is a confusion factor when considering AD symptomatology. For BD, the more the number of clinical signs used the greater the likelihood suffering symptoms.

Symptomatology associated with accommodative and binocular vision anomalies

PURPOSE

To determine the symptoms associated with accommodative and non-strabismic binocular dysfunctions and to assess the methods used to obtain the subjects' symptoms.

METHODS

We conducted a scoping review of articles published between 1988 and 2012 that analysed any aspect of the symptomatology associated with accommodative and non-strabismic binocular dysfunctions. The literature search was performed in Medline (PubMed), CINAHL, PsycINFO and FRANCIS. A total of 657 articles were identified, and 56 met the inclusion criteria.

RESULTS

We found 267 different ways of naming the symptoms related to these anomalies, which we grouped into 34 symptom categories. Of the 56 studies, 35 employed questionnaires and 21 obtained the symptoms from clinical histories. We found 11 questionnaires, of which only 3 had been validated: the convergence insufficiency symptom survey (CISS V-15) and CIRS parent version, both specific for convergence insufficiency, and the Conlon survey, developed for visual anomalies in general. The most widely used questionnaire (21 studies) was the CISS V-15. Of the 34 categories of symptoms, the most frequently mentioned were: headache, blurred vision, diplopia, visual fatigue, and movement or flicker of words at near vision, which were fundamentally related to near vision and binocular anomalies.

CONCLUSIONS

There is a wide disparity of symptoms related to accommodative and binocular dysfunctions in the scientific literature, most of which are associated with near vision and binocular dysfunctions. The only psychometrically validated questionnaires that we found (n=3) were related to convergence insufficiency and to visual dysfunctions in general and there no specific questionnaires for other anomalies.

Can chronic visual discomfort measures accurately predict acute symptoms?

PURPOSE

Several surveys exist to determine the severity and frequency of chronic symptoms related to visual discomfort. To our knowledge, there are no studies that investigate the potential of chronic visual discomfort ratings to predict acute discomfort symptoms that are experienced after tests of accommodation and vergence. We examined the ability of two measures of chronic visual discomfort symptoms to predict acute symptoms experienced.

METHODS

The Conlon et al. and the convergence insufficiency symptom surveys were administered to 40 participants to assess chronic visual discomfort symptoms. Two measures were used to assess acute symptoms. The first consisted of four Likert-scaled questions relating to comfort level during last test, visual distortions or movement, discomfort caused by overhead lights, and presence of headache symptoms. These questions were asked before and after binocular examination, and the scores were used to generate a postexamination symptom score. The second measure of acute symptoms consisted of participants rating their general discomfort on a four-point Likert scale after each binocular test, and the ratings were summed to produce a General Symptom Score. Participants were then categorized into a high or low Post-exam symptom group and General symptom group. Data were analyzed with a binary logistic regression to determine whether the chronic surveys could predict acute symptom group classification.

RESULTS

Approximately 75% of predictions were accurate for either chronic symptom survey. Headache, soreness, and eye-related questions were more reliable predictors of symptom acute outcome.

CONCLUSIONS

These data suggest that the Conlon and Convergence Insufficiency Symptom Survey (CISS) surveys are good predictors of acute symptoms induced during a binocular examination and validate the use of chronic symptom surveys as screening tools for symptomatic binocular dysfunction. Further investigation is required to determine predictability of accommodative or vergence performance.

Diagnostic validity of clinical signs associated with a large exophoria at near

Purpose. To analyze the diagnostic validity of accommodative and binocular tests in a sample of patients with a large near exophoria with moderate to severe symptoms. Methods. Two groups of patients between 19 and 35 years were recruited from a university clinic: 33 subjects with large exophoria at near vision and moderate or high visual discomfort and 33 patients with normal heterophoria and low visual discomfort. Visual discomfort was defined using the Conlon survey. A refractive exam and an exhaustive evaluation of accommodation and vergence were assessed. Diagnostic validity by means of receiver operator characteristic (ROC) curves, sensitivity (S), specificity (Sp), and positive and negative likelihood ratios (LR+, LR-) were assessed. This analysis was also carried out considering multiple tests as serial testing strategy. Results. ROC analysis showed the best diagnostic accuracy for receded near point of convergence (NPC) recovery (area = 0.929) and binocular accommodative facility (BAF) (area = 0.886). Using the cut-offs obtained with ROC analysis, the best diagnostic validity was obtained for the combination of NPC recovery and BAF (S  =  0.77, Sp = 1, LR+ = value tending to infinity, LR- = 0.23) and the combination of NPC break and recovery with BAF (S  =  0.73, Sp = 1, LR+ = tending to infinity, LR- = 0.27). Conclusions. NPC and BAF tests were the tests with the best diagnostic accuracy for subjects with large near exophoria and moderate to severe symptoms.

Effectiveness of vision therapy for convergence dysfunctions and long-term stability after vision therapy

BACKGROUND

Symptomatic convergence insufficiency (CI) is a common binocular dysfunction. It is often associated with accommodative insufficiency (AI). Optimum therapy for this condition was recently shown to be in-clinic vision therapy (VT). More scientific studies are needed to assess the effectiveness of VT and verify these evidence-based results.

METHODS

Fifty-seven children aged 9-13 years were diagnosed with symptomatic CI (n = 27) or combined symptomatic CI and AI (n = 30). They were independently divided into a treatment and a control group, matched by age and gender. The treatment group received 12 weeks of VT while the control group received no therapy. A quality of life instrument documented the symptomatic patients and charted improvement in symptoms after therapy. Clinical aspects were also assessed to determine the treatment effects on clinical findings. Twenty children in the treatment group completed a 1 year follow-up examination.

RESULTS

Symptom scores and clinical measures of the treatment and control groups were not significantly different at baseline (p > 0.05), but showed significant differences after completion of 12 weeks of treatment (p < 0.001). No significant changes of either symptoms or signs were evident for the control group. One year follow-up examination revealed that most children maintained the improved symptom and clinical measures after VT.

CONCLUSION

This study supports the notion that VT is a successful method of treating CI and CI combined with AI.