Year : 1992 | Volume
: 40 | Issue : 1 | Page : 2--4
Involvement of the eye and orbit in neurofibromatosis type 1
CH Gaonker, AK Mukherjee, Madhavi Pokle
Department of Ophthalmology, Goa Medical College, Panaji-Goa, Pin 403 001, India
C H Gaonker
Department of Ophthalmology, Goa Medical College, Panaji-Goa, Pin 403 001
11 individuals were diagnosed to have neurofibromatosis type 1 and were examined for evidence of any ophthalmic lesions. Lisch nodules were the commonest manifestation of the disease and were present in 73% of all the patients (88% of those aged 16 years or more). 55% of the cases showed presence of neurofibroma on the lids. Other findings were optic glioma, unilateral sphenoid dysplasia with enlarged orbit, medullated nerve fibers and prominent corneal nerves with an incidence of 9% each.
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Gaonker C H, Mukherjee A K, Pokle M. Involvement of the eye and orbit in neurofibromatosis type 1.Indian J Ophthalmol 1992;40:2-4
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Gaonker C H, Mukherjee A K, Pokle M. Involvement of the eye and orbit in neurofibromatosis type 1. Indian J Ophthalmol [serial online] 1992 [cited 2021 May 6 ];40:2-4
Available from: https://www.ijo.in/text.asp?1992/40/1/2/24418
Neurofibromatosis (NF) has been reported from all parts of the world and has no racial or sexual preponderance . As many as seven forms of the disease have been described . However, the knowledge at the present time is sufficient to clearly distinguish neurofibromatosis type 1 (previously known as Von Recklinghausen or peripheral neurofibromatosis) and type 2 (bilateral acoustic or central neurofibromatosis); and further subclassification is unjustified by the inadequate evidence . Neurofibromatosis type 1 (NF1) is the commonest form accounting for over 90% of all the cases ; with a prevalence of around 1/4950 (20,10 ) of population . Inheritance is autosomal dominant and approximately 50% of cases represent new mutations. The diagnostic criteria adopted by the 1987 National Institute of Health (NIH) Consensus Development conference on neurofibromatosis are shown in [Table 1] . The major defining features of NF1 are cafe au lait spots, peripheral neurofibromas and Lisch nodules.
Lisch nodules (Iris hamartomas) described in the previous literature with no particular significance have received special importance in the recent reports ,,,. These are lightly pigmented, gelatin like lesions resembling nevi found on all parts of the surface of the iris. They are virtually pathognomonic of the disease and over the last few years, they have acquired a definitive role to establish or exclude the diagnosis of NF1 ,. The involvement of the other tissues of the eye and the orbit is common and scarcely any tissue or structure within or around the eye, except the lens seems immune ,. The present communication deals with ophthalmic evaluation of 11 cases of NF1, with a special emphasis on the incidence of Lisch nodules. This, to our knowledge is one of the rarest studies on NF1, carried out in the Indian population in recent years.
MATERIAL AND METHODS
The diagnosis of NF1 was based upon the criteria shown in [Table 1]. The routine ophthalmic assessment included
1 Examination of the ocular adnexa and motility
2 Measurement of visual acuity
3 Slit-lamp examination of the anterior segment of the eye
4 Examination of the fundus with direct and indirect ophthalmoscope.
5 Indentation tonometry
7 Retinoscopy and
8 X-ray orbit - Caldwell view and optic foramina views.
1 Of the 11 patients, 8 were males and 3 were females, ranging in age from 9 to 35 years. All of them belonged to the Indian race.
2 [Table 2] depicts the incidence of various ophthalmic findings.
Lisch nodules were the commonest in incidence, seen in 8 of 11 patients (73%) and were bilateral in all 8 (100%). They were present in 7 of the 8 patients above the age of 16 years (88%). In most cases they could be appreciated with the naked eye, and their presence was confirmed by slit-lamp examination. They appeared as dome shaped lesions with a smooth outline, light brown in colour and varying in size and number (2 to 32)
3 4 of the 6 patients with neurofibromas of the lids showed fibroma molluscum whereas the remaining 2 had plexiform neurofibromas presenting with ptosis. All cases showed involvement of the upper lid unilaterally. In one patient the plexiform neurofibroma was extending into the temporal region and was associated with a palpable bony defect in the temporal fossa.
4 2 patients presented with unilateral proptosis. In one of them, the proptosis was reducible and pulsatile in nature and was associated with neurofibroma of the upper lid. X-ray revealed the absence of greater wing of the sphenoid with enlargement of the orbit on the affected side. The other patient showed enlarged optic foramina radiologically and was proved to be a case of glioma of the optic nerve.
Lisch nodules are the commonest ophthalmic manifestation of NF1 , They begin to develop in early childhood and are present in over 95 % adults with the disease . Histologically they are melanocytic hamartomas containing various amount of pigment  and therefore are presumed to be of neural crest origin embryonically, as are the other manifestations of NF1- cafe au lait spots and cutaneous neurofibromas . Their incidence, though on the lower side in this series is still comparable with the previous reports [Table 3].
Neurofibromas involving the upper lid present with ptosis and the characteristic S-shaped contour of the upper lid forms a distinctive and diagnostically very suggestive picture of NF1. Its incidence of 55% in the present series is relatively higher than the report of Huson et al who detected their presence in 16% of the cases . Plexiform neurofibromas are known to be associated with bony deficiencies involving the temporal region, occipital bone, sphenoid with absence of orbital roof, and part of sella turcica as well as the general enlargement of the orbit . These deformities may be present as a congenital defect or they may arise as a result of erosion by the tumour . The pulsatile proptosis represents the transmitted cerebral pulsations caused by the herniation of brain tissue into the orbit through such defects and is differentiated from the other causes of pulsatile proptosis especially carotico-cavernous fistula by the absence of the characteristic bruit and the prominent conjunctival vessels .,,
Approximately 10 to 20% of the gliomas arising in the optic nerve and chiasma are known to be associated with NF1 ,. In the series of Holt, optic gliomas were found in 23% of children with NF . Congenital medullation of the nerve fibres and prominent corneal nerves have also been described in NF .,
The absence of choroidal hamartomas and glaucoma in this report is striking. Choroidal hamartomas were reported to be present in 51% of the patients by Lewis and Riccardi ; and in 35% of the patients by Huson et al . As many as 50% of cases of NF with involvement of the lids and face exhibit glaucoma on tl -e affected sides. These eyes with glaucoma show distinctive gonioscopic findings . No abnormalities were detected in our patients on gonioscopic examination. This may be attributed to the comparatively less number of patients comprising this study. The small size of the sample also explains the relatively low incidence of Lisch nodules in this series [Table 3]. In conclusion Lisch nodules are undoubtedly the commonest ocular manifestation of NF1; and the involvement of the eye and the orbit in the disease shows no differences in the Indian population.
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