|Year : 1994 | Volume
| Issue : 3 | Page : 139-143
Familial nanophthalmos : Management and complications
Arvind Neelakantan, Priya Venkataramakrishnan, B Sridhar Rao, N Krishnan, L Vijaya, Sheila John, Bibhas Kar
Medical & Vision Research Foundation, Madras, India
B Sridhar Rao
Medical Research Foundation, 18 College Road, Madras 600 006
Source of Support: None, Conflict of Interest: None
Nanophthalmos is a rare form of congenital hypermetropia, in which, the individual is at a high risk of developing angle-closure glaucoma. We report a family of nanophthalmos affecting a brother and sister, as confirmed by biometry. Genetic analysis revealed an autosomal recessive mode of inheritance. The sister developed angle-closure glaucoma, which was refractory to medical and laser therapy. She underwent surgical interventions which resulted in complications. The clinical presentation, management, and complications encountered are discussed
Keywords: Nanophthalmos - Angle-closure glaucoma
|How to cite this article:|
Neelakantan A, Venkataramakrishnan P, Rao B S, Krishnan N, Vijaya L, John S, Kar B. Familial nanophthalmos : Management and complications. Indian J Ophthalmol 1994;42:139-43
|How to cite this URL:|
Neelakantan A, Venkataramakrishnan P, Rao B S, Krishnan N, Vijaya L, John S, Kar B. Familial nanophthalmos : Management and complications. Indian J Ophthalmol [serial online] 1994 [cited 2020 Sep 21];42:139-43. Available from: http://www.ijo.in/text.asp?1994/42/3/139/25572
Nanophthalmos (dwarf eye) is a rare form of congenital microphthalmos, in which, the eye is reduced in volume without the presence of other gross ocular or systemic abnormalities.sub Such eyes have a characteristic disparity in the proportion of intraocular contents, with a high lens/eye volume ratio and hence a narrow anterior segment. This disparity results in crowding of the anterior segment structures, which leads to pupillary block, contributes to the shallowness of the anterior chamber and results in angle-closure glaucoma. Most nanophthalmic cases apparently occur sporadically although familial cases are occasionally seen . 
We present two siblings with nanophthalmos. One of them had associated glaucoma. The clinical features, inheritance, and management were studied.
| CASE 1|| |
A 42-year-old female presented to us in June 1992, with a chief complaint of gradual diminution of vision in both eyes since 2 years. She gave a history of wearing aphakic-like spectacles since childhood. On enquiry she revealed that her younger brother too wore similar type of spectacles (case 2). Her best corrected visual acuity was 6/60; N10 in the right eye and 6/18; N10 in the left eye. Her spectacle correction in the right eye was +22.00 Dsph/+1.00 Dcyl X 180 degrees and +21.00 Dsph/+1.75 Dcyl X 180 degrees in the left eye, respectively. Slit-lamp examination showed clear corneas with marked iris convexity in both the eyes. The peripheral anterior chambers were slit-like. Applanation tonometry recorded a pressure of 22 to 36 mm Hg in the right eye and. 23 to 37 mm Hg in the left eye. The wide variation in the recording was due to the large ocular pulse fluctuation. On compression gonioscopy, bilateral synechial angle closure was present. Funduscopy revealed hyperopic discs with a cup/disc ratio of 0.3 in both the eyes.
A clinical diagnosis of nanophthalmos was made at this juncture, and the patient underwent A-and 13scan ultrasonography. The biometry results are shown in the [Table - 1]. The ultrasonography substantiated the diagnosis of nanophthalmos. No choroidal detachment was noticed in the B-scan.
A neodymium: YAG laser peripheral iridotomy was performed in both the eyes in August 1992, under the cover of topical 1% apraclonidine (lopidine, Alcon labs Fortworth, TX). Following the laser iridotomies the peripheral anterior chamber in both eyes deepened minimally, but gonioscopy continued to show bilateral angle closure. The patient was advised to use 2% pilocarpine eye drops 4 times a day, along with 0.5% timolol maleate, twice a day in both the eyes.
On examination in November 1992, the iridotomies were found to be patent and the peripheral anterior chambers were very shallow. An intraocular pressure (lOP) of 22 mm Hg was recorded in both the eyes. The gonioscopic and optic disc pictures remained unchanged. She underwent a bilateral argon laser iridoplasties (using a 500 micron spot size at 0.5 second exposure and 350 mW power) following which the irides contracted well and the anterior chambers deepened. However, the synechial angle closure continued to persist.
The patient reported to us again in March 1993, with a complaint of diminished vision in the right eye. She was regularly using her antiglaucoma medications. Her best-corrected visual acuity was 6/ 60; N18 and 6/24; N10 in the right and left eyes, respectively, with her previous correction. Slit-lamp examination continued to show markedly convex irides with patent iridectomies, bilateral nuclear sclerosis, and posterior subcapsular cataracts [Figure - 1]. Gonioscopy failed to show angle structures even on compression. The IOP was 26 mm Hg and 23 mm Hg in the right and left eyes, respectively. A surgical intervention was considered at this stage due to failure of both medical and laser therapies.
Due to the high risk of intraocular surgery in these eyes and the good results reported by Wax et al [4 ] we performed a four quadrant anterior lamellar sclerectomy in the right eye, with sclerotomies in the inferior scleral beds in May 1993.
In the early postoperative period, the anterior chamber deepened remarkably [Figure - 2]. On examination in August 1993, the right eye still showed a deep peripheral anterior chamber, whereas the left eye continued to show the preoperative picture. An IOP of 26 mm Hg was recorded in both the eyes. In view of the good results seen with this procedure in the right eye, the same was performed in the left eye in August 1993. In August 1993, the visual acuity in the left eye decreased to counting fingers due to progression of cataract, she was advised cataract surgery in the left eye. At this time the intraocular pressure was 26 mm Hg in the right eye and 20 mm Hg in the left eye. Extracapsular cataract extraction was performed in the left eye in September 1993. Intraocular lens (IOL) implantation was planned but could not be performed due to severe positive pressure during surgery. In the early postoperative period there was iris prolapse through the wound, A pars plana vitrectomy with wound repair was done 6 days following cataract extraction in view of the positive vitreous pressure. During the vitrectomy massive choroidal detachments with a total retinal detachment was noted. Vitrectomy without base excision was performed, followed by a fluid/air exchange and silicone oil injection. In December 1993, her best-corrected visual acuity was counting fingers at 2 metres in the right eye and 6/60; N12 in the left eye. The decreased vision in the right eye was due to worsening of her senile cataract. Intraocular pressure of 32 mm Hg and 14 mm Hg were recorded in the right and left eyes, respectively. The retina was attached in the left eye.
| CASE 2|| |
A 34-year-old male, younger brother of case 1 presented to us for an ocular examination. His best-corrected visual acuity was 6/12; N8 and 6/18; N10 in the right and left eyes, respectively. He accepted a correction of +17.00 Dsph/+1.25 Dc X 160 degrees in the right eye and +17.50 Dsph/+0.75 Dc X 170 degrees in the left eye. Slit-lamp biomicroscopy revealed clear corneas, with minimally shallow peripheral anterior chambers. The 1OP recorded was 12 mm Hg in both the eyes. Gonioscopy revealed a narrow angle entry, but on compression all angle structures were visible in both eyes till the scleral spur. The optic discs were hyperaemic with a cup/ disc ratio of 0.2 bilaterally. A-and B-scan ultrasonography were performed and the biometry measurements recorded are shown in the [Table - 1]. The B- scan was normal and the A-scan measurements confirmed the diagnosis of nanophthalmos. No treatment was offered, but he was advised a detailed ocular examination including applanation tonometry and dynamic gonioscopy every 4 to 6 months.
Genetic analysis [Figure - 3] showed that two out of five siblings, one male and one female, were affected. Nanophthalmos was limited to this sibship and there was no historic evidence that other members of the pedigree were involved. No history of consanguinity could be elicited. Analysis of this pedigree revealed a definite autosomal recessive (ar) inheritance pattern. Incidentally, the nanophthalmic family were Bengali Brahmins, a caste in which intra-caste marriages are known to be common, which in this case may or may not be significant.
| Discussion|| |
Glaucoma in nanophthalmic eyes has been treated with laser iridoplasty, surgical iridectomy, filtration surgery, cataract extractions and vortex vein decompression. Unfortunately, these procedures are accompanied by an extremely high complication rate both intraoperatively and postoperatively. 
Cross and Yoder have reported a nanophthalmic family with four affected individuals.  Consanguinity could not be established in their family, but based upon the origins of the family, they have proposed an ar pattern of inheritance. A few pedigrees compatible with autosomal dominant (ad) inheritance have been reported.  While the occurrence in our reported cases is a stronger evidence for ar inheritence, it still may not be a conclusive evidence, since non-genetic aetiologies or unrecognized hereditary causes such as ad with incomplete penetrance in one of the parents, may be operating.
The most common cause of the development of glaucoma in such eyes is the disparity in the ocular dimensions (an increased lens volume/eye volume ratio).  Another mechanism thought responsible for the angle-closure glaucoma is the development of uveal effusion.  The serous choroidal detachment and secondary retinal detachment cause forward rotation of the ciliary body, relaxation of lens zonules, forward movement of the lens, increasing the iridolenticular apposition, and pupillary block resulting in the angleclosure glaucoma. Singh and Simmons  have categorized patients into three groups based upon the clinical findings on retinal evaluation.
Case 2 was categorized into group 1 (Angle open, IOP < 20 mm Hg). These eyes have a high propensity for angle-closure glaucoma and hence periodic gonioscopy at intervals of 3 to 4 months is suggested with careful documentation of the gonioscopic findings. The frequency of angle-closure glaucoma in such eyes is highest in 40 to 70 year age group.  Case 1 had already progressed into group 3 (Angle partially or totally closed, 1OP > 20 mm Hg) at the time of initial evaluation. In such eyes medical and laser management of the glaucoma is indicated and intraocular surgery is performed only when absolutely necessary . 
In concurrence with other reports, laser iridotomies in this patient did not help in controlling the IOP as the procedure does not alter the basic aetiology namely the high lens/eye volume ratio.  Laser iridoplasty is the recommended procedure for these eyes, once the iridotomy fails to control the pressure. Bilateral iridoplasty with additional medical therapy failed to bring the IOP under control, necessitating surgical intervention. The A- and B- scan ultrasonography helped provide confirmation of our clinical diagnosis [Table - 1] and also exclude posterior segment pathology such as choroidal effusion in these cases.
Due to the high risk of postoperative uveal effusion in such eyes, it was decided to perform a prophylactic scleral "thinning" with preplaced sclerotomies, before undertaking a filtering surgery. Reports by Brockhurst and Jin et al  have shown this procedure to be beneficial in reducing the incidence of uveal effusion that occurs with ocular surgery. Wax et al  have reported deepening of the anterior chamber, control of the intraocular pressure and an uneventful postoperative period with anterior lamellar sclerectomies.
In the procedure originally described by Brockhurst,  large scleral beds were dissected at the equator, to decompress the vortex veins hi the hope of relieving the uveal effusion that occurs either intraoperatively or postoperatively in such eyes. Gass  used the same procedure to treat a case of uveal effusion successfully, as he thought that the abnormally thick sclera was the cause for the effusion. However, the procedure as described by Wax et all and as performed by us differed from that of Brockhurst" and Gass,  in that the scleral flap did not extend posteriorly to the equator and no attempt was made to unroof or transect the vortex veins. Wax et al suggested that the thickened sclera in nanophthalmos, may have mostly an anterior component and by thinning it, the improved transcleral fluid outflow results in functional decompression of the anterior vascular bed, thus preventing the dreaded postoperative complications.
Jin and Anderson  have reported uncomplicated cataract surgeries following unsutured sclerotomies. We performed the four quadrant anterior lamellar sclerectomy with inferior sclerotomies to help avoid the perioperative complications. The anterior chambers deepened remarkably following the procedure, however, this did not prevent the complications of cataract surgery. We feel that the inferior unsutured sclerotomies close with time and thus are of no value in the long-term prevention of complications. Though reports in the literature ,,, suggest various methods to prevent complications of intraocular surgery in nanophthalmic eyes, we are of the opinion that intraocular surgery in these eyes must be undertaken with extreme caution.
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[Figure - 1], [Figure - 2], [Figure - 3]
[Table - 1]