670 Br J Ophthalmol 1999;83:670–675 Chronic cortical visual impairment in children: aetiology, prognosis, and associated neurological Br J Ophthalmol: first published as 10.1136/bjo.83.6.670 on 1 June 1999. Downloaded from deficits Richard Huo, Susan K Burden, Creig S Hoyt, William V Good Abstract Our final aim was to assess visual improve- Background/aims—To evaluate preva- ment among our cohort of CVI patients. To lence, aetiology, prognosis, and associated that end, we devised a method for grading the neurological and ophthalmological prob- functional visual perception of our CVI pa- lems in children with cortical visual tients. In those patients who returned for impairment (CVI). follow up visits, we calculated the amount of Methods—The records of 7200 outpatients improvement between visits. seen in the paediatric ophthalmology prac- tice over the past 15 years were reviewed in Materials and methods order to compile data concerning CVI. In We reviewed the records of approximately addition, the authors devised and applied a 7200 patients who were seen from 1979 to system for grading visual recovery in order 1994 in a large paediatric ophthalmology refer- to assess prognosis. ral practice (WVG, CSH). At the time of the Results—CVI occurred in 2.4% of all patient’s appointment, the diagnosis of “CVI” patients examined. The four most com- was based upon (1) vision loss in the absence mon causes of CVI were perinatal hypoxia of signs of anterior visual pathway disease, or (22%), cerebral vascular accident (14%), (2) vision loss greatly exceeding that which meningitis (12%), and acquired hypoxia would be expected, given the findings of an (10%). Most children with CVI had associ- ocular examination. Children with nystagmus ated neurological abnormalities. The underwent an electroretinogram (ERG), and most common were seizures (53%), cer- we carefully excluded all children where poor ebral palsy (26%) hemiparesis (12%), and visual function could be entirely attributed to hypotonia (5%). Associated ophthalmo- non-cortical deficits. logical problems were esotropia (19%), Evaluation of these files revealed 170 cases exotropia (18%), optic nerve atrophy of CVI. Data were subsequently derived in a (16%), ocular motor apraxia (15%), nys- number of areas. tagmus (11%), and retinal disease (3%). http://bjo.bmj.com/ On average, CVI patients improved by two levels as measured by the authors’ scale. AETIOLOGY AND ASSOCIATED NEUROLOGICAL DEFICITS Conclusion—The majority of children with CVI showed at least some recovery. The aetiology and neurological assessments In this group of children, CVI is often were based on the historical and physical find- accompanied by additional ophthalmo- ings, as well as laboratory tests. In most cases logical problems and is nearly always abnormal neurological findings were obvious. associated with other, serious neurologi- However, the diagnosis of seizure and hearing on October 1, 2021 by guest. Protected copyright. cal abnormalities. loss required historical (for example, chart Department of review) corroboration and/or verification with Ophthalmology, (Br J Ophthalmol 1999;83:670–675) University of other healthcare providers. In cases of in utero California, San drug exposure, the aetiology was initially Francisco, CA, USA Cortical visual impairment (CVI) has emerged presumed to be cocaine exposure, and the R Huo as the leading cause of low vision in children in diagnosis of cocaine exposure was corrobo- CSHoyt developed countries.1–3 Over the past 10 years, rated by other neurological findings known to occur in conjunction with this drug’s toxicity University of Michigan researchers have endeavoured to elucidate incidence, prevalence, aetiology, prognosis, (small size for gestational age, prematurity, Medical School, Ann 13 Arbor, Michigan, USA and associated neurological and ophthalmo- central nervous system infarction). S K Burden logical problems in CVI.4–7 These studies have been performed in various regions of the ASSOCIATED OPHTHALMOLOGICAL DEFICITS Smith-Kettlewell Eye world, but there is a paucity of data on the epi- Assessment of ophthalmological problems was Research Institute, San Francisco, CA, USA demiology of CVI in the United States. made by the members of this team (WVG, W V Good We therefore undertook the review of a large CSH) at the time of each patient’s appointment. paediatric ophthalmology referral practice to Many patients reported multiple aetiologies, Correspondence to: determine the occurrence of CVI within this neurological problems, or ophthalmological William V Good, MD, Smith-Kettlewell Eye population. We determined the frequencies of deficits. We counted each of these responses Research Institute, 2232 various aetiologies of CVI and recorded neuro- separately even though this meant counting the Webster Street, San logical and ophthalmological problems associ- same patient many times. We then calculated the Francisco, CA 94115, USA. ation with CVI, particularly since other studies percentage of our population that had multiple Accepted for publication of CVI often excluded children with ophthal- entries for aetiology, and associated neurological 18 December 1998 mological abnormalities.8–12 and ophthalmological abnormalities. Chronic cortical visual impairment in children 671 LEVEL OF VISION Table 2 Aetiologies associated with CVI patients in the We assessed each patient’s functional vision study population (n=170) Br J Ophthalmol: first published as 10.1136/bjo.83.6.670 on 1 June 1999. Downloaded from using the following nomenclature: level 1 if the % of study patient could only perceive light at the time of No of population examination; level 2 if the patient could Aetiology patients (n=170) occasionally visually fixate on large objects, Perinatal hypoxia 38 22.35 faces, or movement in the environment, as Cerebral vascular accident 24 14.12 Meningitis/encephalitis 21 12.35 noted in the patient’s chart; level 3 if visual Acquired hypoxia 17 10.00 function was highly variable, but with at least Hydrocephalus 16 9.41 some moments of good visual fixation as indi- Idiopathic 16 9.41 Premature (<34 weeks’ gestation) 13 7.65 cated by (1) the ability to see small objects Intracranial cyst 9 5.29 (such as pennies or stickers), or (2) could reli- Head trauma 7 4.12 ably visually fixate a face; level 4 if a patient Seizures 7 4.12 Congenital microcephaly 5 2.94 could reliably fixate on small targets and/or Brain tumour 4 2.35 with visual acuity that could be measured in In utero drug exposure 3 1.76 the range of 20/400 to 20/200; level 5 if there Other 11 6.47 was good, reliable visual fixation and/or with visual acuity (at least with both eyes open), Among the study population (n=170), 154 measured not better than 20/50 at the time of CVI patients had known aetiologies. This rep- examination; level 6 if there was a completely resented 90.6% of the study population. normal sensory visual examination. These cri- Sixteen CVI patients had idiopathic onset of teria are summarised in Table 1. CVI (9.4% of the study population). Some We implemented this system as a method of patients reported multiple aetiologies (21 quantifying functional vision. The assessment patients or 12.4%). of vision in levels 5 and 6 included visual acu- The most common aetiology for CVI within ity measurement, but we included a behav- this population was perinatal hypoxia (22.4% ioural component in the rating scale to account of our 170 cases). Cerebral vascular accident for the possibility of good acuity but poor accounted for 14.1% and meningitis/ cognition/verbal skills. The initial level of vision encephalitis for 12.4%. Next in frequency were was ranked for each of the 170 CVI patients. acquired hypoxia (10.0%), hydrocephalus For those patients that returned for follow up, (9.4%), and prematurity (7.7%). Other less we noted level of vision at his or her last visit. common aetiologies included intracranial cyst, We then calculated visual improvement as 5.3%; head trauma, 4.1%; seizures, 4.1%, and expressed in levels of improvement. brain tumour, 2.9%. In utero drug exposure (cocaine in particular) was thought to to be PATIENT AGE aetiological in 1.8% of cases. In 9.4% of cases Each patient’s age was recorded in years. we could not determine an aetiology for CVI. These results are summarised in Table 2. HOMONYMOUS HEMIANOPSIA Most of our CVI patients suVered neurologi- http://bjo.bmj.com/ We recorded the occurrence of homonymous cal and/or ophthalmological deficits. Thirty hemianopsia in CVI patients. two patients had ophthalmological deficits alone (18.8%), 51 patients had neurological Results deficits alone (30.0%), and 79 patients had Review of the patient records revealed 170 both neuro- and ophthalmological deficits cases of CVI, 2.4% of all patients seen. From (46.5%). Only eight patients (4.7%) had no these 170 patients, we were able to construct a associated neuro- or ophthalmological deficits profile for the CVI patients. The average patient (see Fig 1). on October 1, 2021 by guest. Protected copyright. age was 3 years. Initially, the average level of Seventy five per cent (n=128) of our patients vision was 2.1 as measured by our scale. Thirty had at least one associated neurological abnor- eight patients (22.4%) had homonymous hemi- mality. Within this group, 50.8% (n=65) had anopsia in addition to CVI. one neurological deficit, 40.6% (n=52) had Ninety six patients returned for further two neurological deficits, and 8.6% (n=11) evaluation (56.5% of the study population). had three neurological deficits. Among those