|Year : 2021 | Volume
| Issue : 2 | Page : 262-264
An unusual case of a rotating toric phakic intra-ocular lens
Y Umesh, Devika Singh, Anand Balasubramaniam
Department of Cornea and Refractive Services, Sankara Eye Hospital, Bengaluru, Karnataka, India
|Date of Submission||19-Aug-2020|
|Date of Acceptance||29-Dec-2020|
|Date of Web Publication||01-Apr-2021|
Dr. Devika Singh
Department of Cornea and Refractive Services, Sankara Eye Hospital, Varthur Road, Kundalahalli, Bangalore - 560 037, Karnataka
Source of Support: None, Conflict of Interest: None
An accurately sized Phakic Intra-Ocular lens (PIOL) helps achieve adequate vault which in turn also provides for rotational stability. Toric PIOL implantation was done for a case with bilateral myopic astigmatism. Both eyes had similar spherical equivalent and ocular biometric parameters; thus, same sized PIOLs were implanted. Right eye post-operative course was uneventful but left eye repeated rotation was noted. An inadvertently placed smaller sized PIOL in left eye could explain rotation. Re-evaluation confirmed similar ocular and PIOL parameters in both eyes, but a shallow vault (444 μ) in left eye compared to right (602 μ). Post PIOL extraction, measurement confirmed the left PIOL size to be lesser (11.61 mm) than the expected size (12.75 mm).
Keywords: Rotation, Toric phakic intra-ocular lens, vault
|How to cite this article:|
Umesh Y, Singh D, Balasubramaniam A. An unusual case of a rotating toric phakic intra-ocular lens. Indian J Ophthalmol Case Rep 2021;1:262-4
Posterior chamber Phakic Intra-Ocular Lens (PIOL) is a boon for correction of refractive errors in patients who are not ideal candidates for ablative laser procedures. Implantable phakic contact lens (IPCL- v2 – Caregroup Solutions, India), is a similar option for patients in developing countries. Rotational stability is crucial to achieving effective astigmatic correction in a Toric IPCL (T-IPCL).
| Case Report|| |
A 23-year-old female patient with high myopic astigmatism presented to our OPD for refractive surgery. Her corrected distance visual acuity (CDVA) was 20/20, N6 in both eyes with a manifest refractive error of –7.50/–2.0 × 10 (OD) and –7.00/–3.00 × 165 (OS). Both eyes anterior and posterior segment examination was unremarkable.
After evaluation, the option of T-IPCL implantation was given. Internal Anterior chamber depth (ACD) as measured by Lenstar (LS 900, Haag Striae, USA) was 3.31 mm (OD) and 3.22 mm (OS). Horizontal White to White (WTW) measurement using digital calliper was 11.7 mm (OU) while Sulcus to Sulcus (STS) on Ultrasound Biomicroscopy was 12.26 mm (OD) and 12.21 mm (OS).
T-IPCL of size 12.75 mm was implanted in the right eye as per manufacturer recommendations. Surgery was uneventful. On the first post-operative day, CDVA right eye was 20/20. On slit lamp examination, anterior chamber was deep, TIPCL axis was aligned with grade 3 subjective vault height. The IOP was normal and objective vault size was 602 μ on Anterior Segment Optical Coherence Tomography.
Further, as per manufacturer recommendation, a similar sized T-IPCL was placed in the left eye. Immediate postoperative period was uneventful, but CDVA dropped from 20/20 to 20/120 at 2 weeks post-surgery. There was no history of trauma. On examination, anterior segment was unremarkable with an adequate grade 2 vault, normal IOP with clear lens. T-IPCL axis was found to be rotated by 70 degrees. Subsequently, T-IPCL re-alignment, followed by a thorough ophthalmic viscoelastic device wash was done. A similar degree of T-IPCL re-rotation was noted 3 days after re-surgery.
Considering repeated rotation, the preoperative ocular parameters were re-checked. Re-evaluation confirmed same measurements as obtained earlier. Repeat UBM confirmed similar values of STS, absence of iris cysts, similar ACDs, and lens rise [Figure 1].
|Figure 1: UBM scan at 9 o'clock transverse section, showing T-IPCL in situ, no anatomical malformations and Sulcus To Sulcus (STS) size of 12.26 mm and 12.21 mm of right and left eye respectively (a and b)|
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The vault size measured was 602 μ and 444 μ in right and left eye respectively, checked in ambient light conditions, mesopic pupil and patient not accommodating [Figure 2]. Presence of a shallow vault in the left eye compared to the right eye indicated the possibility of a inadvertently placed smaller T-IPCL in the left eye. Smaller sized T-IPCL are known to frequently rotate from desired axis, thus the manufacturers were requested for a larger sized T-IPCL. The patient was planned for T-IPCL extraction and a larger size T-IPCL was implanted. The extracted lens was examined immediately. The haptic footplates were undamaged and the size measurement by digital calliper was 11.61 mm in comparison to the expected size of 12.75 mm [Figure 3].
|Figure 2: Post-operative anterior segment and AS-OCT image of right eye (OD) showing an accurately placed horizontal T-IPCL (a) with the vault size of 602 microns (b). Post-operative image of left eye (OS) showing a rotated T-IPCL axis (c) and a vault size of 444 microns (d)|
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|Figure 3: Digital caliper measurement of the freshly extracted T-IPCL in the Operation Theatre, recording the size of 11.61 mm|
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After the replacement procedure, uncorrected vision at 1- and 6-month follow-up was 20/20, with a well-aligned TIPCL and grade 3 vault.
| Discussion|| |
The vault size of a PIOL is determined by various predictors related to ocular anatomy and PIOL features. Parameters like WTW, STS, ACD, pupil size and axial length (AL) have a positive correlation,,, whereas a high crystalline lens rise (CLR), low ACD value, and older age have a negative correlation, with the vault size. PIOL feature like spherical equivalent (SE) correlates negatively with vault height whereas size correlates positively.,
Rotational stability of Toric-PIOL is in turn determined by the vault size obtained. Undersized PIOLs are associated with a smaller vault, and possess a higher chance of spontaneous rotation. For Non-Toric PIOLs, lens rotation can be a simple surgical technique for correction of inadequate vault size thus avoiding lens exchange.
The IPCL design includes 6 haptics with a footplate spring effect to increase stability. It has an angled optic-haptic giving a steeper mid-peripheral rise which provides a buffer capacity to maintain the vault despite under-sizing. It is stored in a balanced salt solution and does not enlarge after implantation. A customized T-IPCL lens is always placed along the horizontal axis (0-180 degrees), not requiring any rotation, thus eliminating misalignment. Proper haptic footplate unfolding and secure placement in ciliary sulcus are essential for its rotational stability.
Here we report a case of T-IPCL implantation in a patient with bilateral similar myopic astigmatism with different outcomes. The patient had bilaterally identical ocular symmetry and as per nomogram same sized T-IPCL was implanted. Due to repeated T-IPCL rotation in left eye, ocular parameters were rechecked, which were consistent.
On close observation, though the vault achieved in both eyes was within acceptable range, left eye vault size was significantly lesser compared to the right eye. Inter-eye vault variability was suspected to be due to the smaller IPCL sizing which also explained the lack of rotational stability. Left IPCL extraction and replacement with a larger sized lens finally provided for toric stability. Suspicion of smaller size of the IPCL was confirmed with the measurement of the extracted IPCL.
| Conclusion|| |
Our case highlights the importance of quantitative vault measurement for both adequate sizing and rotational stability of a T-IPCL. Though infrequent, despite an accurate clinical work-up, surgeon may encounter an inadvertently placed wrong-sized IPCL. Source of the wrong-sized phakic lens may originate at any stage from the manufacturing lab to the operation theatre. Potential causes may include erroneous technical production, mislabelling, and human errors. Identification of the cause and the optimal solution lies in the analytical clinical judgment of the surgeon.
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
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]