FP1271 : Cortical Visual Impairment (CVI).

Dr.Sarthak Suresh Kothari, K20241, Dr.S Priya

Introduction

CVI is the disorder predominantly referring to visual loss caused by some disturbance to the posterior visual pathway or visual cortex which encompasses difficulty in processing and interpreting incoming visual information. CVI is the leading cause of visual impairment in children in the west, and it’s probably become leading cause overall in future.

There are very strict protocols put in place for children who are born prematurely and who may have immature retinas and are at risk for detached retinas. There are also protocols put in place for when children should have their eyes examined, and there are all kinds of recommendations from the American Academy of Paediatricsabout vision care for children. But there is no protocol in place to monitor or identify children with CVI. There are 3 components to diagnose CVI: first, that the child has an eye exam that does not explain the way they see. The second part is that the child also has a history of some neurologic event. And the third is that the children with CVI have the presence of ten characteristic behaviours. Children with CVI present with different strengths and weaknesses than children with other types of visual impairment, this necessitates a critical rethinking of the traditional interpretations of visual impairment because interventions conducive to increasing performance with ocular impairments may be largely ineffectual or even detrimental when used for children having cortical visual impairments.

Objectives

• To evaluate etiology, andassociated neurological, radiological and ophthalmic findings of children with CVI
• To shed more light onto behavioral characteristics.
• To estimate the extent of visual improvement with appropriate individualized rehabilitation of children.

Material and Methods:

1. Study Population: All children who presented to Neuro-ophthalmology clinic of Aravind Eye Hospital Pondicherry from 2014 to 2017.
2. Study Site: Neuro-Ophthalmology clinic in Aravind Eye Hospital Pondicherry.
3. Study Design:Retrospective Study
4. Study Size:68 Children
5. Study Period:Jan’14 to Dec’17. A minimum of 1-year regular follow-up was conducted. 
6. Inclusion criteria:

• All children, presenting to Aravind Eye Hospital Pondicherry, diagnosed with CVI–> whose parents/ guardians are willing to give consent to participate in study.
• Com
• Exclusion Criteria:
• Children with any other ocular conditions like congenital glaucoma, cataract, corneal disorders, anterior segment dysgenesis and retinal diseases which are unrelated to CVI or its treatment.
• Children with any major systemic diseases.
• Methodology:

All children who presented to us, detailed history regarding birth, NICU admission, behavioral patterns, habits and preferences etc. were inquired. Complete ocular examination including visual acuity, cycloplegic refraction, ocular alignment and motility, tonometry, fundus examination, visual fields, electro-physiological tests and neuro-imaging was done.The diagnosis of CVI was made when the ophthalmological findings did not explain the visual performance of the child or there was associated neurological pathology.

Roman-Lantzy CVI range was used to evaluate functional vision, level of CVI and also to design interventions. The children were rehabilitated in individualized manner with methods apt for their degree of CVI. Minimum follow-up plan of 1-year was devised with initial 1-month weekly visits, fortnightly visits for next 2 months, monthly for next 3 months and quarterly then after. Parents were also instructed to continue home based interventions daily. Ocular examination, responses to stimuli were evaluated at each subsequent visit.

Outcomes 

• To identify causes and associated ophthalmic, behavioral, neurological & radiological findings of children with CVI in South Indian population.
• To knowthe effect of individualized rehabilitation on visual improvement in children with CVI. 
• Ethical Considerations:The study was conducted as per Declaration of Helsinki guidelines. Informed consent was obtained from parents/ guardian of patients to participate in study,which will be free of coercion and undue influence and choice to decline participation, would be made available.

Statistical Analysis:

Frequency (Percentage) or Mean (SD) will be used to evaluate the data. Chi-square test or Fisher’s exact test will be used to assess the association between categorical variables. Student’s t-test will be used to assess the difference between continuous variables. P-value less than 0.05 considered as statistically significant. All statistical analysis will be done by using STATA 11.1 (Texas, USA).

Results:

Causes:Hypoxic/ischemic accidents (49%) are leading cause of CVI. Second most common cause of CVI were complications of prematurity (20%) or other gestational/delivery difficulties. Albeit, prematurity per se doesn’t cause CVI but there might be micro-bleeds or minute other abnormalities which aren’t yet picked up by current diagnostic tests.  CVI can also result from later occurring events that result in decreased cortical oxygen and/or damage to brain tissue such as cardiac arrest/respiratory failure, increased intracranial pressure, head trauma, hydrocephaly, and/or shunt failure (7%).   Congenital brain malformations (6%) secondary to genetic syndromes and/or other birth defects are also implicated in the incidence of CVI, as are CNS infections like meningitis, cytomegalovirus, encephalitis, and herpes simplex. Finally, secondary complications suchas seizures, metabolic diseases, hypoglycemia, and progressive genetic syndromes (5%) may cause or intensify cortical visual impairments. However, in sizeable (29%) population, no cause could be identified.

Ocular Findings: Most children with CVI may have no notable eye disorders. Strabismus (55%) may be noted and could be an early sign of corticalvisual impairment, especially if consistent exotropia (29%) is present.  In addition to possible strabismus, a slight motornystagmus may also be present in the form ofan unsteady gaze or poorly coordinated/jerky eye movements.  This motor nystagmus (23%) is normally the direct result of impaired cortical control and should not be confused with the sensory nystagmus often seen in children with ocular visual impairments. Refractive errors were seen in 45% children (however, refractive errors are common in premature child and also there tends to be hyperopic shift in children which needs to be accounted). Fundus examination could be normal or show unilateral/ bilateral disc pallor (32%) or ocular hypoplasia (9%) or signs of prematurity (ROP – 4%). Visual fields examination revealed 12% children had B/L lower field impairment (corresponds to their inability to pick objects from floor or see obstacles on ground) and 3% had homonymous hemianopia.

Behavioral presentations:The overwhelmingpresence of visual latency, poor visual attention/limited visual attention span, andextremely shortened gaze behaviors is noted as most frequently reported hallmarks ofchildren having CVI, often resulting in frequent misperceptions of these children asinattentive, or malingering. Students with CVI have also been observed to create close viewing situations bybringing objects very near their face and eyes, and up to one-third of childrenwith CVI show a characteristichead turn, usedto reduce the numberof items in the visualfield (decrease visual crowding), to maintainvisual attention, and toallow for selective peripheral viewing areoften misinterpreted aspurposeful gaze aversion, task rejection. Children with CVI often are really drawn to things that have highly saturated colours (commonly red and yellow), towards movement (stare at ceiling fan), or towards light. They don’t blink when you touch them at the bridge of the nose, or don’t blink in response to visual threat. They have a liking towards a familiar object at a close distance in a controlled environment (can’t make out familiar toy amongst many toys or at a distance of more than 4 feet).

Neurological findings:Most commonly child has some form of developmental delay (65%). Other neurological findings seen were seizures (19%), cerebral palsy (12%), microcephaly (3%), hemiparesis (2%) and hearing loss (5%).

Radiological findings:Predominant radiological findings were those due to hypoxic ischemic encephalopathy (HIE), periventricular leukomalacia (PVL), cortical atrophy and CNS structural anomalies.

Interventions

So the real expectation is the child moves through the range and that we monitor those changes, we adapt the environments and materials as we see those improvements with the expectation that the child will continually improve their vision.

Interventionswere based on CVI Range assessment:

• Phase I: 0 to 4 on the Scale

• Phase II: 4 to 7 on the Scale
• Phase III: 7 to 10 on the Scale

 

Phase 1:Building visual attention

It includes:- Providing a controlled environment (no visual clutter, no music/talking, no distracting smells); Selecting a familial single favourite colour object with lights or against backlighting, either moving or reflective material within 2 feet of child; Providing sufficiently long wait time. Gradually we can progress towards similar looking objects.

Phase 2: Embedding vision into function

It includes:- Providing aminimal controlled environment (less visual clutter, mild music/talking, smells, do not adjust lightings); Selecting a familiar object & associating it with sounds; at a farther distance (4-6 feet). Child demonstrates latency only when it’s tired, blinks inconsistently in response to touch and its attention can be diverted from light. We can see that child responds to patterns, 2-3 coloured toys and can pick out a 3-D object on being shown its 2-D picture.

Phase 3: Resolution of CVI characteristics

It includes:- Providing normal environment (but with less visual clutter); multi-coloured objects within 20 feet. Child has no colour or pattern or movement preference; can adapt to novel objects; can identify the “same” image even when the background array differs slightly; demonstrates blink response to visual threat consistently; and can look and reach as a single action. Latency is rarely present.

In our 62 % of these children showed mild to moderate visual improvement with visual rehabilitation in 1 year. This demonstrates that rehabilitation improves in vision and thus quality of life in children. So, it is of utmost importance that we continue to enhance this ever-improving vision to the place at which a child can have a much higher level of functional vision.

Conclusion:

Major risk factor for CVI is perinatal hypoxia. Child with CVI can have varied clinical presentations and behaviors, which needs to be detected and rehabilitated at an early age for better visual outcomes. Vision stimulation and rehabilitation results in mild to moderate recovery in quite a majority of cases.