Iridoschisis: Spectrum of Presentation

Abstract

PURPOSE:

The purpose of the study was to report a small case series of patients with iridoschisis seen at our hospital over a period of 5 years.

METHODS:

Retrospective review of all those files over the past 5 years whereby the diagnosis of iridoschisis/iris atrophy/iris fibrils in anterior chamber (AC) was made.

RESULTS:

In our case series, the average age at presentation was 49 years (range: 23–85 years). The pathology was bilateral in 57% of patients in our series. Our most common presentations were angle closure glaucoma and cataract. Younger individuals can also manifest iridoschisis.

CONCLUSION:

The iridoschisis can be an incidental finding, and gonioscopy should be performed in all the cases, as occludable or synechiael angle closure may be present in these cases.

Introduction

Iridoschisis is a rare condition with 100 odd cases reported from all over the world. It is characterized by partial cleavage of the iris. The anterior layer of the iris stroma floats freely in the anterior chamber (AC). This condition was first described in 1922 by Schmitt. The term iridoschisis (iris splitting) was first introduced in 1945 by Lowenstein and Foster, who found a deep, parallel cleft between the anterior and posterior stromal layers of the iris. The most common age of presentation is sixth to seventh decades of life. Most of the cases are bilateral and sectoral affecting the inferior quadrants of iris tissue. The etiopathogenesis is not clear but is mostly considered as an age-related atrophy. Secondary iridoschisis can occur posttrauma or prolonged instillation of miotics. The condition is usually detected incidentally as a defect in the iris or associated with angle closure glaucoma in 50% of the cases. The mechanism by which iridoschisis causes angle closure is not certain. Some have speculated that the free floating anterior stromal fibers may bow forward and come in contact with the trabecular meshwork causing elevation of intraocular pressure (IOP) and angle closure. Others have proposed that the pigment released from the stromal atrophy may clog the trabecular meshwork. Visual morbidity in these cases can occur from corneal decompensation secondary to iridocorneal touch or glaucoma.[1,2,3,4,5,6,7,8]

This was a retrospective review of all those files over the past 5 years whereby the diagnosis of iridoschisis/iris atrophy/iris fibrils in AC was made. All the cases of iridoschisis presenting to our hospital over a period of 5 years are detailed in our case series highlighting their varied presentations and management. The case series adheres to the Tenets of Declaration of Helsinki and our institutional review board approved it. The simplified details of the patients in our case series are given in Table 1, highlighting the demographic details, laterality and site of iridoschisis, pupil/iris status, and the clinical presentation.

Table 1.

The demographic details, laterality and site of iridoschisis, presentation, and pupillary status in patients of our case series

Age (years)	Sex	Laterality of iridoschisis	Presentation		Site of iridoschisis	Pupil status
			Right eye	Left eye
60S	Female	Bilateral	PAC	PACG-acute angle closure attack	Inferior	Pupillary peaking at 1o’clock in right eye and 10-12 o’clock in the left eye, iris pigments present over anterior lens capsule
55	Female	Bilateral	PACS	PACG+CRVO+cataract	Inferior	Irregular pupil from 4-8 o’clock position and iris pigments present over anterior lens capsule in left eye, pupillary ruff lost from 3-5 o’clock position in the right eye
60	Female	Unilateral (other eye could not be commented upon due to PBK)	PACS+cataract	PBK	Inferior	Irregular pupil from 4-5 o’clock in the right eye
23	Male	Bilateral	JOAG	JOAG	Superior	Vertically oval pupil in both eyes
85	Male	Unilateral	IMSC	Pseudophakia	Inferior	Irregular pupil from 4-7 o’clock in the right eye
28	Male	Unilateral	Incidental finding	WNL	Superior	Vertically oval pupil in the right eye
35	Female	Bilateral	Chronic ACG-prephthisical eye	PACG	Inferior	Irregular pupil from 4-7 o’clock position in both eyes

PAC: Primary angle closure, PACS: PAC suspect, PACG: PAC glaucoma, ACG: Angle closure glaucoma, JOAG: Juvenile open angle glaucoma, IMSC: Immature senile cataract, PBK: Pseudophakic bullous keratopathy, CRVO: Central retinal vein occlusion, WNL: Within normal limits

Case Reports

Case 1

A 60-year-old female presented with painful diminution of vision with nausea for past 2 days. On evaluation, best-corrected visual acuity (BCVA) was 6/9 in the right eye (RE) and finger counting at 2 m in the left eye (LE). IOP as measured by Goldmann Applanation Tonometry was 11 and 48 mmHg in RE and LE, respectively. Microcystic corneal edema with shallow AC was seen in LE. Multiple thin disintegrated iris fibrils were seen floating in the AC from 5 to 7 o'clock in RE and from 4 to 8 o'clock in LE [Figure 1a and b]. Gonioscopy showed 180° and 360° peripheral anterior synechiae (PAS) in RE and LE [Figure 2], respectively. Laser peripheral iridotomy (PI) was done in both eyes. Lens showed early nuclear sclerosis with a cup-disc ratio of 0.5:1 in RE and 0.6:1 with inferior rim thinning in LE. Corresponding superior arcuate defect was seen on visual fields in LE. She was diagnosed as a case of bilateral iridoschisis presenting as unilateral acute angle closure attack. A combination of two antiglaucoma medications (AGMs) was started in both eyes. On her 6-month evaluation, the patient had an IOP of 12 and 14 mmHg in RE and LE, respectively.

Figure 1.

(a and b) Slit lamp photograph of (a) right eye, (b) left eye showing multiple thin disintegrated iris fibrils floating in the anterior chamber from 5 to 7 o'clock and from 4 to 8 o'clock respectively along with patent peripheral iridotomy in both eyes

Figure 2.

Slit lamp gonioscopy photographs in all the quadrants of the left eye showing 360° peripheral anterior synechiae

Case 2

A 55-year-old female presented with BCVA of 6/18 in RE and 6/24 in LE. IOP was 18 and 20 mmHg, respectively. AC was shallow in both eyes with Relative Afferent Pupillary Defect in LE. Iridoschisis fibrils were seen from 3 to 5 o'clock position in RE and 4–8 o'clock position in LE. Gonioscopy showed 360° PAS in LE with occludable angles in RE. Lens showed nuclear sclerosis Grade 3 in both eyes with a cup-disc ratio of 0.5:1 and 0.9:1 with no rim >180° in RE and LE, respectively. She also has dot blot hemorrhages in all quadrants with macular edema in LE. She was diagnosed as a case of bilateral iridoschisis with unilateral advanced angle closure glaucoma and central retinal vein occlusion in LE and primary angle closure suspect in the fellow eye. She underwent phacotrabeculectomy with mitomycin C with intraocular lens (IOL) implantation following intravitreal avastin in LE. Laser PI was done in RE. She had an IOP of 12 and 10 mmHg on her 6^th-month follow-up in RE and LE, respectively. The iris tissue from the iridoschisis site as well as the iridectomy site was sent for histopathology evaluation which showed collagen fibrils were disproportionately less obvious throughout the stroma with chronic nonspecific inflammatory cells in the iridoschisis iris tissue stroma as compared to the iridectomy iris tissue [Figure 3a and b].

Figure 3.

(a and b) Histopathology photograph (H and E, ×10) of iris tissue from (a) iridectomy site, (b) iridoschisis site showing collagen fibrils were disproportionately less obvious throughout the stroma with chronic nonspecific inflammatory cells in the iridoschisis iris tissue stroma as compared to the iridectomy iris tissue

Case 3

A 60-year-old female presented with BCVA of 6/36 and finger counting 1 m in RE and LE, respectively, with an IOP of 15 mm in both eyes. Iridoschisis was present from 4 to 5 o'clock hour in RE and pseudophakic bullous keratopathy (PBK) was seen in LE. Gonioscopy showed occludable angles in RE with nuclear sclerosis Grade 2. Fundus examination showed a cup-disc ratio of 0.4:1 in RE. She was diagnosed as a case of unilateral iridoschisis with occludable angles in RE and cataract and contralateral PBK (presence of iridoschisis could not be commented upon due to poor view due to PBK). Phacoemulsification with IOL implantation was done in RE. Postoperatively, vision was 6/9 with an IOP of 11 mm and normal visual fields. It is also a possibility that the other eye also had associated occludable angles, leading to a complicated surgery and eventually PBK.

Case 4

A 23-year-old male presented for routine eye checkup with an IOP of 29 and 26 mm in RE and LE, respectively. On ocular evaluation, iridoschisis was present from 12 to 3 o'clock position in RE and multiple iridoschisis fibers were present at 6, 7, 10, and 11 o'clock in LE. Gonioscopy showed open angles in both eyes. Fundus evaluation showed a cup-disc ratio of 0.6:1 with bipolar thinning in both eyes with corresponding field defects. He was diagnosed as a case of iridoschisis with bilateral juvenile open angle glaucoma. The patient was started on 3 AGMs. On 5^th-year follow-up, IOP was 14 mm in both eyes.

Case 5

An 85-year-old male presented with unilateral inferior iridoschisis with cataract and underwent phacoemulsification with PCIOL- Posterior chamber intraocular lens implantation. He had an IOP of 14 mm in both eyes with open angles on gonioscopy and a disc with a cup-disc ratio of 0.4:1 in both eyes. The contralateral eye was pseudophakic.

Case 6

A 28-year-old male presented with unilateral superior iridoschisis detected incidentally on routine evaluation. There was no clinical evidence of glaucoma even after 5 years of follow-up.

Case 7

A 35-year-old female presented with bilateral inferior iridoschisis with chronic angle closure glaucoma and cataract in both eyes. RE was prephthisical eye with IOP of 6 mmHg. PI followed by prescription of 2 AGMs was done in LE. On her 6^th-year follow-up, IOP was 16 mm in RE and 14 mm in LE. She was advised to undergo combined cataract and glaucoma surgery in LE.

Discussion

We present a short case series of seven patients with iridoschisis highlighting the varied presentation of this clinical finding along with differences in their management. To the best of our knowledge, this is the largest case series on iridoschisis.

In our case series, the average age of presentation was 49 years-5^th decade (youngest being 23 years and oldest being 85 years) although the literature search has pointed out that the most common age of presentation is in the sixth to seventh decades of life.[1,2,3,4,5,6,7,8] Males and females were almost affected equally in the ratio of 1.33:1 although the literature search shows it to be more common among females.[1,2,3,4,5,6,7,8] The pathology was bilateral in 57% of patients in our series with 43% of the cases being unilateral also suggesting that additional factors in between the two eyes other than age might be responsible for iridoschisis. Iridoschisis fibrils were present inferiorly in 71% of patients. The patients with superior iridoschisis were of the age of 23 and 28 years suggesting that younger age might have a bearing on iridoschisis in these patients and might not be age-related atrophy in these younger patients. All the patients in our case series had brown iris due to the demographic distribution and genetics of our area. Furthermore, it was observed in our series that irregular pupil was present in those quadrants which had iridoschisis fibrils, especially in those involving the pupillary margin. In patients with iridoschisis fibrils not involving the pupillary margin, they had pupillary peaking/notching in the quadrants opposite to the clock hours, in which iridoschisis was present. The most common presentation in our case series was glaucoma (57%) with 75% of patients presenting with angle closure glaucoma and only one case with open angle glaucoma. Four out of seven patients underwent yttrium–aluminum–garnet (YAG) laser PI for appositional or synechiael angle closure in our case series. The patient with bilateral open angle glaucoma was a young patient suggesting that the etiopathogenesis of glaucoma and iridoschisis might be varied in the younger patients as compared to the older patients. Two patients presented with cataract and one patient was detected incidentally to have iridoschisis. Those patients who underwent cataract extraction were operated carefully with the copious use of ocular viscoelastic devices (OVDs) to avoid the iris fibrils getting sucked up in the phacoemulsification probe.

Conclusion

This case series suggests that the most common presentation was angle closure glaucoma and cataract independently. Younger population can also have iridoschisis. The finding can be incidental and gonioscopy should be performed in all the cases as occludable or synechiael angle closure may be present in these cases which should undergo prompt YAG laser PI. Disc and field evaluation should be done in all the cases as the most common association is glaucoma in these patients. Early phacoemusification should be done with ample use of OVDs to make the surgery easier.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.