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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 1  |  Issue : 2  |  Page : 105-108

High axial myopia in neurofibromatosis type 1


1 Department of Ophthalmology, Lady Hardinge Medical College and Associated S.S.K.H and K.S.C. Hospital, University of Delhi, New Delhi, India
2 Department of Ophthalmology, University College of Medical Sciences and Associated GTB Hospital, University of Delhi, New Delhi, India
3 Department of Ophthalmology, Lady Hardinge Medical College and Associated Hospitals, University of Delhi, New Delhi, India

Date of Submission02-Mar-2021
Date of Decision06-Apr-2021
Date of Acceptance30-Apr-2021
Date of Web Publication31-May-2021

Correspondence Address:
Dr. Siddharth Madan
Department of Ophthalmology, University College of Medical Sciences and Associated GTB Hospital, University of Delhi, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ipcares.ipcares_71_21

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  Abstract 

Background: Clinicians must be aware of phenotypic variability in neurofibromatosis type 1 (NF 1) presentations. There is perhaps a limited understanding on progression of NF 1 in prepubertal years and the subsequent threat to vision. Progressively increasing myopia may go unnoticed under a severely ptotic eyelid that gathers attention, due to a disfiguring mass in patients with NF 1. High myopia may result in recalcitrant amblyopia if not tackled early with multidisciplinary management. Clinical Description: A 12 year old girl had a history of progressively increasing left upper eyelid ptosis due to an upper eyelid mass, first noticed at the age of 1 year and eventually resulted in severe ptosis by the age of 5 years. However, this went unnoticed until she was diagnosed with NF 1 at the age of 12 years. Best corrected visual acuity was 6/6 (Plano) in the right eye (OD) and counting finger 2 m with − 15.0 diopter spheres in the left eye (OS). Peripheral fundus examination was normal in both eyes. Levo elevation and abduction were limited OS. Hypotropia, pulsatile proptosis, and depression of the globe were clinically attributable to enlargement of orbital tissues and lid problems. Contrast enhanced computed tomography scan revealed plexiform NF with extraconal extensions. Axial length was 21.94 mm OD and 28.92 mm OS. B scan ultrasound revealed a posterior staphyloma OS. Management: The patient underwent a debulking surgery of the eyelid mass which on histopathological examination confirmed plexiform NF. Surgery resulted in a cosmetic reduction in ptosis; however, any intervention was relatively too late to rehabilitate the left eye. Conclusions: Eye care certainly has its regional differences. High axial myopia may result in low VA and recalcitrant amblyopia that may go unrecognized and comes with management challenges to the attending ophthalmologist and allied specialties dealing with these cases of NF 1.

Keywords: Anisometropic amblyopia, high axial myopia, neurofibromatosis type 1, optic pathway glioma


How to cite this article:
Garg R, Madan S, Yadav N, Yadav R. High axial myopia in neurofibromatosis type 1. Indian Pediatr Case Rep 2021;1:105-8

How to cite this URL:
Garg R, Madan S, Yadav N, Yadav R. High axial myopia in neurofibromatosis type 1. Indian Pediatr Case Rep [serial online] 2021 [cited 2021 Jun 19];1:105-8. Available from: http://www.ipcares.org/text.asp?2021/1/2/105/317366

Neurofibromatosis type 1 (NF 1, also known as von Recklinghausen disease) is one of the most common genetic disorders. Several ophthalmic associations exist which include the characteristic Lisch nodules, retinal or choroidal hamartomas, retinal ischemia, optic pathway gliomas, or congenital glaucoma.[1],[2] Anterior scleral staphyloma has also been documented in the literature.[3] Reduction in visual acuity (VA) is commonly attributed to an underlying optic pathway glioma. However, that may not always be true. The point worth describing this case is to alert clinicians and primary eye care professionals of one such presentation of NF 1 that results in a reduction in VA accompanied with management challenges as was observed in a 12-year-old girl.


  Clinical Description Top


The child was apparently well till the age of 1 year when she was detected with unilateral ptosis in the left eye (OS) due to an upper lid mass. At this stage, the ptosis was reportedly mild for which the parents never sought an ophthalmic consultation and no documentation was made of ptosis severity and VA assessment. By the age of 5 years, there was severe ptosis attributed to the eyelid mass involving the entire left upper eyelid. The parents were too apprehensive to allow a corrective surgery for ptosis as explained by a local physician at village although the nature of this mass remained unknown as no formal specialist opinion was sought. No comment was made on the VA at this stage. The child never realized that the vision in her left eye was significantly reduced as she was mostly dependent on her apparently normal right eye with good visual acuity for carrying out her daily activities binocularly and this continued for last seven years dating from her current presentation at 12 years of age. In her current presentation at 12 years, she was diagnosed with NF 1[Figure 1]a, [Figure 1]b based on the presence of clinical signs which included a plexiform neurofibroma of the left upper eyelid, multiple Lisch nodules on the iris along-with café-au-lait macules over her neck, back, trunk, bilateral legs and arms [Table 1].[1],[2],[3]
Figure 1: Patient presented with left upper eyelid plexiform neurofibroma (a). Globe hypotropia was seen with eyelid thickening (b). Contrast-enchanted computed tomographic scan revealed the presence of plexiform neurofibroma having extraconal extensions causing proptosis (c), dysplasia of the left sphenoid wing (c and d), and loss of volume of the temporal lobe (d). Right eye was normal on B-scan (e). Left eye had increased axial length (c and f)

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Table 1: Diagnostic criteria for neurofibromatosis type 1

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Management and Outcome

In this presentation to an ophthalmologist, unaided acuity was 6/6 in the right eye and counting finger at 1 m OS. Best-corrected VA was 6/6 (Plano) in the right eye (OD) and counting finger 2 m with − 15.0 diopter spheres OS. Until all this time, there was no awareness of refractive error/amblyopia, and no management of either of these was undertaken. Right eye was essentially normal [Figure 1]a and [Figure 1]c,[Figure 1]d,[Figure 1]e. The difference in marginal reflex distance 1 between two eyes was more than 4 mm with a poor levator function (less than 4 mm), pointing to severe ptosis OS causing complete occlusion. Levo-elevation and abduction were limited OS. Hypotropia, pulsatile proptosis, and depression of the globe were observed and were clinically attributable to enlargement of orbital tissues and lid problems. Both eye media were clear. Indirect ophthalmoscopy revealed that the right eye fundus was within normal limits, and the left optic disc was large with a cup to optic disc ratio of 0.4:1, parapapillary atrophy, and a normal periphery. Atrophy with a normal periphery on indirect ophthalmoscopy. Contrast-enhanced computed tomography scan confirmed the presence of PN having extraconal extensions, causing globe hypotropia, dysplasia of the left sphenoid wing, and loss of volume of the temporal lobe [Figure 1]c and [Figure 1]d. Left vitreous cavity appeared enlarged and so was the left globe axial length [Figure 1]c and [Figure 1]f. Further, axial length measurement on A-scan showed a markedly increased value for the left eye (21.94 mm OD; 28.92 mm OS). B-scan ultrasound revealed a posterior staphyloma [Figure 1]f. She underwent a debulking surgery of the upper eyelid neurofibroma, which on histopathological examination confirmed plexiform NF. To add, both eyes always maintained normal intraocular pressures throughout (OD 15 mmHg, OS 16 mmHg).


  Discussion Top


Manifestations of NF 1 can be extremely unpredictable. Newly diagnosed cases require close observation with ophthalmological examination and imaging. A comprehensive examination should be performed by the eye health professional at least every 6 months throughout the period of visual development up to the age of 8 years as this is the critical period during which amblyopia may develop.[4] The frequency of examinations is increased if orbital–periorbital PN (OPPN) is rapidly growing. At every visit, the eye care professional should assess VA, intraocular pressure, and ocular motility and perform cycloplegic refraction to monitor for the development of amblyopia, glaucoma, strabismus, optic nerve disease, ptosis, proptosis, or a cavernous sinus involvement. Anisometropic amblyopia may result due to ptosis or increased axial length and has been observed in up to 43% of children with OPPN.[1],[4] Stimulus deprivation amblyopia resulting from significant ptosis has been reported in roughly one-third to one-half of patients. However, the current body of literature for unilateral myopia in NF is limited and so is the association of high myopia in NF 1.[2],[5],[6] This has been suggested in a study conducted by Lévy et al. that the release of growth mediators by the neurofibroma affects the globe locally via autocrine and paracrine signaling defects possibly due to a significant upregulation of genes and causes eyeball enlargement.[6] Nearly thirty genes that were studied were found to be upregulated which encoded transcription factors, growth factors, secrete proteins, cytokines, and their receptors.[6] Hoyt, Billson and other co-authors have supported the role of local growth factors in progressive globe enlargement that can be observed in NF1 independently of intraocular hypertension/glaucoma. Whether to attribute the pathogenesis of the development of staphyloma to the absence of the sphenoid wing or orbital roof remains uncertain as of now.[3] Optic pathway glioma in children with NF 1 is not associated with increased prevalence of anisometropia. Both stimulus deprivation and anisometropia were contributors to the development of amblyopia in this case.[7],[8] Clinical studies do suggest that the incidence of myopia is significantly higher in children with unilateral congenital ptosis, but this is a rare finding in humans unlike the animal experiments.[7] The severe ptosis that was fully established by the age of 5 years in this child possibly may have worked like an artificial lid stitch limiting eye opening. It might have deprived the developing globe of a clear retinal image, hence hindering the normal physiological process of emmetropization culminating in asymmetric enlargement of the axial length. This mechanism of axial myopia has been studied in animal experiments on tree shrews and rhesus monkeys.[7],[9] Ptosis may usually induce some corneal astigmatism in the affected eye which however was absent in this child, and therefore, the sole contribution of this acquired ptosis in inducing myopia to the extent of −15.00 D seemed unlikely yet not totally impossible. Amblyopia normally coexists with strabismus and refractive errors, which include astigmatism, anisometropia, and ametropia that can manifest as amblyopia, irrespective of the presence of ptosis. Surgical management in cases with progressively increasing OPPN is still debatable and is dependent on the judgment of the clinician. Unfortunately, no confident evidence-based recommendations with a long follow-up exist.[10] Complete removal of OPPN surgically in early childhood is feasible in only a small subset of affected patients as the tumor is diffuse and involves the surrounding region or the organ in a widespread manner. OPPN growth following surgery in younger patients is well known. Although a debulking surgery at an early stage to reduce the degree of ptosis may be an attempt to prevent stimulus deprivation, the above-mentioned facts compromise the functional outcomes of surgery in NF and the prognosis remains poor. Surgery did reduce the mechanical ptosis in the patient, but it at this stage was relatively late to rehabilitate the left eye and reverse deep amblyopia that had already set in as a result of high axial myopia. Wearing corrective spectacles remained a challenge with the postsurgery tumor size and so was the amblyopia therapy.

This case highlights the fact that small OPPN restricted to the eyelid presenting as mild ptosis may go unnoticed and so is the presence of associated high axial myopia that might also go undetected if timely refraction is not performed. The knowledge of occurrence of this entity must be known to all physicians, nurses, and other healthcare providers, especially the primary healthcare worker screening for visual and structural eye problems in a nonspecialist setting. Prompt reference to an eye healthcare professional at an early stage is necessary. Management decisions depend on case to case basis over a life time of follow-up and should include the input from a multidisciplinary team of general practitioner, neuro-oncology, optometry/ophthalmology/neuro-ophthalmology, craniofacial and plastic surgery, and genetics. The fact that directing all focus toward a disfiguring mass and hunting for diagnosing optic pathway glioma as a possible etiology for amblyopia with a significant battery of tests should not be the rule. A basic investigation like refraction to predict evolving amblyopia early may direct holistic management of these children.



Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's father has given consent for images and other clinical information to be reported in the journal. The patient's father understands that the names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Oystreck DT, Morales J, Chaudhry I, et al. Visual loss in orbitofacial neurofibromatosis type 1. Ophthalmology 2012;119:2168-73.  Back to cited text no. 1
    
2.
Dotan G, Keren S, Stolovitch C, et al. Increased prevalence of ametropia in children with neurofibromatosis type 1 disease. J Child Neurol 2015;30:113-6.  Back to cited text no. 2
    
3.
Kinori M, Armarnik S, Listernick R, et al. Neurofibromatosis type 1-associated optic pathway glioma in children: A follow-up of 10 years or more. Am J Ophthalmol 2021;221:91-6.  Back to cited text no. 3
    
4.
Avery RA, Dombi E, Hutcheson KA, et al. Visual outcomes in children with neurofibromatosis type 1 and orbitotemporal plexiform neurofibromas. Am J Ophthalmol 2013;155:1089-94.e1.  Back to cited text no. 4
    
5.
Chen JY, Muecke JS, Brown SD. Orbital plexiform neurofibroma and high axial myopia. Ophthalmic Plast Reconstr Surg 2008;24:284-6.  Back to cited text no. 5
    
6.
Lévy P, Bièche I, Leroy K, et al. Molecular profiles of neurofibromatosis type 1-associated plexiform neurofibromas: Identification of a gene expression signature of poor prognosis. Clin Cancer Res 2004;10:3763-71.  Back to cited text no. 6
    
7.
Sherman SM, Norton TT, Casagrande VA. Myopia in the lid-sutured tree shrew (Tupaia glis). Brain Res 1977;124:154-7.  Back to cited text no. 7
    
8.
Shimada Y, Horiguchi M. Equatorial staphyloma associated with neurofibromatosis type 1. Case Rep Ophthalmol 2016;7:384-8.  Back to cited text no. 8
    
9.
Gusek-Schneider GC, Martus P. Stimulus deprivation myopia in human congenital ptosis: A study of 95 patients. J Pediatr Ophthalmol Strabismus 2001;38:340-8.  Back to cited text no. 9
    
10.
Avery RA, Katowitz JA, Fisher MJ, et al. Orbital/periorbital plexiform neurofibromas in children with neurofibromatosis type 1: Multidisciplinary recommendations for care. Ophthalmology 2017;124:123-32.  Back to cited text no. 10
    


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