Biometric and AS-OCT findings in angle recession

Dr. Prerna Agrawal, Dr. Sarang Lambat, Dr. Prabhat Nangia, Dr. Vinay Nangia.

Case Description

A male, 19 years of age, presented to us on April 29^th, 2023. He had a history of blunt trauma to the left eye (LE) with a plastic ball 8 years back. There is also a history of LE retinal laser 5 years back. The best corrected visual acuity was 6/6 with Plano in the right eye (RE) and 6/6 with +3.25D in the LE. The RE anterior segment examination was within normal limits.  The LE anterior segment showed a deeper anterior chamber compared to the RE.   Intraocular pressure in RE was 13 mmHg, and in the LE, it was 23 mmHg. On RE gonioscopy, the ciliary body band was seen, and LE showed 360-degree angle recession.

On fundus examination, both eyes disc was normal and the retina was attached. Retinal laser marks posterior to the vitreous base avulsion in inferotemporal quadrant was present in LE. The axial length of RE and LE was 24.21 mm and 25.12 mm respectively. The central corneal thickness in RE and LE was 561µ and 592µ the aqueous depth (AQD) was 3.42 mm and 3.92 mm, and the lens thickness was 3.24 mm and 3.74 mm respectively. 

Fig. 1a. Anterior segment imaging of the RE showed an open angle.
Fig. 1b. Anterior segment imaging of the RE showed the contour of the normal open angle (red marking).

Fig. 6 Color photograph of the fundus of the RE shows a cup disc ratio of 0.4 with a normal neuroretinal rim (red arrow). The retinal nerve fiber layer shows a normal white reflex (yellow arrow).

Fig. 7 Color photograph of the fundus of the LE shows a cup disc ratio of 0.35 with a normal neuroretinal rim (red arrow). Retinal nerve fiber layer shows a normal white reflex (yellow arrow).

Fig.8 Right eye OCT circumpapillary retinal nerve fiber layer (RNFL) showed normal retinal nerve fiber layer (Fig.8b, white arrows) (Fig.8d, black).

Fig.9 Left eye OCT circumpapillary retinal nerve fiber layer (RNFL) showed normal retinal nerve fiber layer (Fig.9b, white arrows) (Fig.9d, black arrows).

Discussion:

Our patient presented for a routine eye examination, and he was found to have elevated IOP in the LE compared to the RE. The asymmetry of IOP was 10 mmHg, with the IOP in the LE being 23 mmHg and in the RE 13 mmHg. In addition, he was found to have 360-degree angle recession in the left eye (Fig.5), which was correlated to a history of blunt trauma in the LE 8 years ago.  Vitreous base avulsion in the LE was also noted in the inferotemporal quadrant.

Development of elevation of IOP, and therefore, glaucomatous damage following angle recession, may take several years to occur. The course is very variable. In our patient, there was only an elevation of IOP but no glaucomatous damage had taken place, as evidenced by a normal optic disc appearance and a normal retinal nerve fibre layer (Fig.7,9).

What is interesting in our patient are the anterior segment findings, as seen with the anterior segment swept-source OCT and the biometric readings. Thus in the LE, the aqueous depth was greater than in the RE (3.92 and 3.42 mm. respectively). The lens thickness was more in the LE compared to the RE (3.74 and 3.24 mm. respectively). The axial length was 25.12 and 24.21 in the LE and RE, respectively. The refractive error was Plano in the RE and +3.25 in the LE. 

The mechanism of damage is thought to be related to the separation of the longitudinal ciliary muscle fibers from the circular muscle fibers. Conceptually, it may mean that they have become a little independent of each other in the area of the angle structures. This leaves the circular muscles free to contract. This would lead to a loosening of the zonules, which may also otherwise have been weakened from the effect of the blunt trauma. This would lead to an increase in the lens thickness. However, the changes in the angle with the iris falling back have also resulted in an increase in the aqueous depth. The effect of these changes, in spite of the relatively greater axial length of the LE, is the development of hypermetropia in the LE. It is advantageous that the injury took place at an age when the visual development had occurred. Otherwise, it may have led to the development of hypermetropia associated with possible amblyopia. This tells us that when we have blunt trauma in childhood, refractive error determination would be important, and a check should be kept on the visual acuity to identify the onset of possible amblyopia.  Likewise, it may be important to do biometry and refraction to identify the potential onset of amblyopia in such patients.

It is interesting to see the change in the shape of the angle in the eye with angle recession, compared to the normal eye. The normal eye shows an angular shape, as is normal for the meeting of the cornea with the angle structures and the iris root.  However, the recessed eye shows that the shape of the angle is now like the smaller side of a rectangle. Please refer to Fig 1a, 1b, 2a, 2b, and 3 to appreciate the contours of the eye. It is evident that the falling back of the iris on the lens, in addition to the zonular weakness, may add to the deepening of the aqueous depth and the backward movement of the lens, associated with the development of the hypermetropia in our patient, whereas, in view of the increased axial length and post-trauma increase in lens thickness one may have expected the development of myopia. 

We decided, in view of the absence of glaucomatous damage, to keep the patient on follow-up and have not yet started anti-glaucoma medication. Our patient may be considered to be at high risk of developing a higher IOP over time and needs to be kept under regular follow-up.

Read Wise

1. Pujari A, Selvan H, Behera AK, Gagrani M, Kapoor S, Dada T. The Probable Mechanism of Traumatic Angle Recession and Cyclodialysis. J Glaucoma. 2020 Jan;29(1):67-70. doi: 10.1097/IJG.0000000000001358. PMID: 31460884.
2. Razeghinejad R, Lin MM, Lee D, Katz LJ, Myers JS. Pathophysiology and management of glaucoma and ocular hypertension related to trauma. Surv Ophthalmol. 2020 Sep-Oct;65(5):530-547. doi: 10.1016/j.survophthal.2020.02.003. Epub 2020 Feb 11. PMID: 32057763.