TNOA Journal of Ophthalmic Science and Research

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 57  |  Issue : 2  |  Page : 113--117

A study on the safety and efficacy of posterior chamber phakic intraocular lens (refractive implantable lens) in high myopia


Sivaviganesh Subramanian, Sharmila Devi Vadivelu, M Ananda Babu, B Meenakshi, Jiz Mary Santhosh 
 Department of Ophthalmology, Regional Institute of Ophthalmology and Government Ophthalmic Hospital, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Sivaviganesh Subramanian
Department of Ophthalmology, Regional Institute of Ophthalmology and Government Ophthalmic Hospital, Chennai, Tamil Nadu
India

Abstract

Background: Myopia is the most common refractive error worldwide causing visual impairment in children and adults. The prevalence of high myopia varies with age and ethnicity. High myopia has been found to be visually debilitating and affects day-to-day activities of the individual. Aim: This study aimed to analyze the efficacy and visual outcomes of posterior chamber phakic intraocular lens-refractive implantable lens (RIL) in high-myopia patients. Methods: This prospective study was conducted in a tertiary care center during February 2017–February 2018. Results: This study included 50 eyes of 34 patients, which showed 82% of eyes had uncorrected visual acuity equal or better than preoperative best-corrected visual acuity and 52% eyes had visual acuity of 6/6. No incidence of cataract was observed in this study. Conclusion: Refractive results after RIL implantation are found to be safe and satisfactory and has favorable visual outcome.



How to cite this article:
Subramanian S, Vadivelu SD, Babu M A, Meenakshi B, Santhosh JM. A study on the safety and efficacy of posterior chamber phakic intraocular lens (refractive implantable lens) in high myopia.TNOA J Ophthalmic Sci Res 2019;57:113-117


How to cite this URL:
Subramanian S, Vadivelu SD, Babu M A, Meenakshi B, Santhosh JM. A study on the safety and efficacy of posterior chamber phakic intraocular lens (refractive implantable lens) in high myopia. TNOA J Ophthalmic Sci Res [serial online] 2019 [cited 2019 Nov 18 ];57:113-117
Available from: http://www.tnoajosr.com/text.asp?2019/57/2/113/266397


Full Text



 Introduction



Myopia is the most common refractive error worldwide causing visual impairment in children and adults. The prevalence of high myopia varies with age and ethnicity. Higher incidence and prevalence of myopia has been reported in the Southeast Asian countries. High myopia has been found to be visually debilitating and handicapping as it affects day-to-day activities of the individual. There are several treatment options such as photorefractive keratectomy, laser-assisted subepithelial keratectomy, laser in situ keratomileusis (LASIK), and epi-LASIK available for correcting high myopia. One of the recent modalities of treatment is with phakic intraocular lens (PIOL). PIOLs are used to treat high myopia or hyperopia with or without astigmatism, who are not fit for LASIK or with mild keratoconus.[1]

PIOL has become widely popular in recent times. They give optimum results with minimal complications. It was first introduced by Strampelli but later modified by Fyodorov. Initially, the anterior chamber (AC) PIOLs were introduced; later, iris-fixated lens was developed.

However, recently, posterior chamber PIOLs were used greatly because of greater efficacy and safety with maximum satisfaction.[2] Posterior chamber PIOL is placed between iris and natural crystalline lens in the ciliary sulcus. PIOL implantation induces significantly fewer ocular higher-order aberrations than LASIK. Moreover, contrast sensitivity was significantly improved after PIOL implantation but unchanged after LASIK in eyes with low to moderate myopia. Thus, even in the correction of low to moderate myopia, PIOL appears to be superior in visual performance to LASIK.[3] However, neither technique caused significant complications.

Treatment of high myopia with posterior chamber PIOLs has been found to be an effective way of correcting high myopia. We have many PIOLs in our market such as Visian implantable collamer lens (ICL) and Verisyse IOL, but we have used refractive implantable lens (RIL) which has been introduced by an Indian company. Our study aims to analyze the efficacy and visual outcome of posterior chamber PIOL RIL in patients of high myopia.

 Methods



Patients presented to cornea and contact lens services at the Regional Institute of Ophthalmology and Government Ophthalmic Hospital, Chennai, were registered during February 2017–February 2018, evaluated, and followed up during the study period. A detailed history of the patient, best-corrected visual acuity (BCVA) using Snellen's chart, slit-lamp examination, fundus examination, retinoscopy, gonioscopy, endothelial count by specular microscopy, central corneal thickness by pachymetry, horizontal vertical iris diameter by Pentacam, white-to-white by digital caliper, A-scan and B-scan ultrasound, and anterior segment-optical coherence tomography (AS-OCT) were done. Endothelial count and AC depth were measured during the presentation and follow-up period. Distance between the anterior surface of PIOL and endothelium (vault) was measured during the follow-up period.

Inclusion criteria

Age >18 yearsStable refraction for 1 yearPatients with myopia >−6.00 DIridocorneal angle >30°AC depth >2.7 mmEndothelial cell count >2500 cells/mm2Central corneal thickness >0.400 mm.

Patients with active anterior segment (AS) disease, recurrent or chronic uveitis, cataract, previous ocular surgery, glaucoma, preexisting macular or retinal pathology, and connective tissue disease are contraindicated for this implantation.

Technique – Under local anesthesia, a small main incision of size 2.8–3.2 mm and two side port incisions were made. Loading of lens into the cartridge should be done with dome up, and we should make sure that the lens is not trapped inside the cartridge. The loaded cartridge is inserted with the bevel down through the main incision after filling up the AC with Ophthalmic Viscosurgical Devices (OVDs). The tip of the injector is kept superficially and the PIOL is injected gently into the AC making sure that the leading hole is on the right [Figure 1], taking care not to damage the anterior capsule of lens or the iris. Then, the lens is gently positioned horizontally with blunt tip manipulator.{Figure 1}

Then, intracameral pilocarpine is used so that the pupil gets constricted and facilitates peripheral iridectomy superiorly [Figure 2]. Preoperative yttrium-aluminum-garnet peripheral iridotomy also can also be performed. OVD is completely extracted, and AC is rehydrated.{Figure 2}

Distance between the anterior surface of PIOL and endothelium (vault) is measured using AS-OCT during the follow-up period. Average vaulting required ranges from 350 to 600 μ. It can also be assessed by comparing it with corneal thickness [Figure 3].{Figure 3}

Ethics

Written informed consent has been obtained from patients for using their details for the study purpose. This study has been approved by the Institutional Ethics Committee.

 Results



The study was conducted on 50 eyes of 34 patients, of which 53% were male and 47% were female. Average age of a patient was 25.24 years with the standard deviation of 5.15 years.

Preoperatively, 30% eyes had BCVA of 6/18, 20% eyes had 6/9, 16% eyes had 6/12, 18% had 6/6, and 8% eyes had 6/24 and 6/36 each [Table 1] and [Figure 4]. Postoperatively, 32% had uncorrected visual acuity (UCVA) of 6/6 and 38% of eyes had 6/9. Twelve percent eyes had 6/12, 10% eyes had 6/18, and 6% eyes had 6/24. In the 1st week, postoperative UCVA was less than preoperative BCVA in 6% of eyes, whereas 94% of eyes had equal or better UCVA than preoperative BCVA. At the end of the 3rd month, all eyes (100%) showed equal or better UCVA than preoperative BCVA (P = 0.000 < 0.05) [Figure 5].{Table 1}{Figure 4}{Figure 5}

Preoperative spherical equivalence for 14% of eyes was between −6.00 D and −10.00 D and 52% of eyes were between −10.25 D and −15.00 D. Remaining 34% of eyes were between −15.25 D and 20.00 D. After 3-month postoperatively, 82% of eyes showed zero spherical error, while 14% of eyes had − 0.50 D and 4% of eyes had –0.50 D–−0.75 D spherical error [Figure 6].{Figure 6}

Preoperatively, 88% of eyes had AC depth between 2.5 and 3.2 mm, and the remaining 12% of eyes had above 3.2 mm. Postoperatively, 94% of eyes had AC depth between 2.4 and 2.8 mm and the remaining 6% of eyes had above 2.8 mm. Although AC depth showed a statistically significant reduction (P < 0.01) it is not below 2.4 mm.

Preoperatively, 64% of eyes had intraocular pressure (IOP) of 10–15 mmHg. Thirty-two percent of eyes had IOP between 16 and 20 mmHg. In the 1st week postoperative, 48% of eyes had IOP between 10 and 15 mmHg and 50% of eyes had between 16 and 20 mmHg. Hence, 98% of eyes had IOP < 20 mmHg (P = 0.01 < 0.05). Only One eye (2%) had IOP > 20 mmHg. In the 3rd week postoperative and 3rd month postoperative, all eyes had IOP <20 mmHg. Postoperatively, 96% of eyes had a reduction in endothelial cell count of <100 cells/mm2 which appeared insignificant. In the 1st week postoperative, 3rd week, and in the 3rd month, all patients had vaulting ranging from 300 to 750 μ.

 Discussion



Although there are many PIOLs RIL [Table 2] in our market, RIL was introduced by one of the Indian companies. It is made up of hydrophilic acrylic material. Four peripheral holes are present in the lens to help aqueous flow [Figure 3]. These lenses have a leading hole on the right and a trailing hole on the left which helps during implantation.{Table 2}

In our study, we have evaluated 50 eyes of 34 patients. The mean age group was 25.24 ± 5.15 years. These patients were followed up for a mean period of 9–12 months. Perzcamtrodi et al. had mean postoperative spherical equivalent (SE) of −1.00 D ±0.50 D, whereas our study showed a mean postoperative SE power of − 0.50 D ± 1.00 D. In our study, postoperative UCVA of 94% eyes were better than preoperative BCVA and 6% eyes were same as preoperative BCVA, whereas in Uusitalo et al. study, 71.9% had equal or better than preoperative BCVA, and Ju et al. study showed 96% eyes had equal or better than preoperative BCVA.[1],[4] In the Food and Drug Administration trials of Visian ICL and Verisyse IOL, 41% eyes and 31% eyes attained UCVA of 6/6 or better, respectively, whereas, in our study, 52% eyes attained UCVA of 6/6.[5]

There was no incidence of cataract in our study, whereas Lee et al. study showed 2%, and Uusitalo et al. study showed 2.6% incidence of cataract.[4],[6] Perzcamtrodi et al. observed that 12% of eyes developed cataract.

Only one eye (2%) had increased IOP during the postoperative period, whereas Ju et al. study observed increased IOP in 8% eyes, and Lee et al. observed in 2% eyes. There was no significant change in endothelial count in our study. Lee et al. study showed 8% decrease in endothelial cells, but it was around 3.5% decrease in endothelial cells in our study [Table 3].{Table 3}

In our study, the mean preoperative AC depth was 3.06 mm and postoperative AC depth was 2.57 mm. There was a significant reduction in AC depth in all patients, but it was not <2.4 mm. Ju et al. also observed a significant reduction in AC depth from 3.5 to 2.5 mm.

Pupillary block was observed in Uusitalo et al. study; pigment dispersion was observed in 6% eyes in Ju et al. study. However, papillary block, pigment dispersion, iritis, and retinal detachment were not observed in our study while observed in other studies.[7]

 Conclusion



According to the results of our study, we conclude that posterior chamber PIOLs (RIL) are safe and effective option for refractive correction. The cataract development, AC depth and changes in IOP were not significant, and vaulting of RIL that were measured in this study. However, for all these patients, a long-term follow-up is needed.

Declaration of patient consent

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

Financial support and sponsorship

This study was funded by Appasamy Associates.

Conflicts of interest

There are no conflicts of interest.

References

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