Visual and refractive outcome of the first intracorneal continuous ring implantation in Sudan

Kamal Hashim Binnawi; Mustafa Abdu

doi:10.4103/1858-540X.158992

CASE REPORT

Year : 2015 | Volume : 7 | Issue : 1 | Page : 16-18

Visual and refractive outcome of the first intracorneal continuous ring implantation in Sudan

Kamal Hashim Binnawi¹, Mustafa Abdu²
¹ National Coordinator for Prevention of Blindness, Khartoum, Sudan
² Department of Contact Lenses, Faculty of Optometry and Visual Sciences, Al-Neelain University, Khartoum, Sudan

Date of Web Publication

17-Jun-2015

Correspondence Address:
Kamal Hashim Binnawi
National Coordinator for Prevention of Blindness, Khartoum
Sudan

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/1858-540X.158992

Abstract

The complete intracorneal ring implantation is the new technique in the management of keratoconus. This case report shows the great effect of this new procedure on the first case that underwent this operation in Sudan. No intraoperative or postoperative complications were seen, and 3 months postoperatively, our subject showed good refractive and visual outcomes.

Keywords: Keratoconus, MyoRing, visual outcome

How to cite this article:
Binnawi KH, Abdu M. Visual and refractive outcome of the first intracorneal continuous ring implantation in Sudan. Sudanese J Ophthalmol 2015;7:16-8

How to cite this URL:
Binnawi KH, Abdu M. Visual and refractive outcome of the first intracorneal continuous ring implantation in Sudan. Sudanese J Ophthalmol [serial online] 2015 [cited 2023 Sep 28];7:16-8. Available from: https://www.sjopthal.net/text.asp?2015/7/1/16/158992

Introduction

Keratoconusis a fairly common bilateral, noninflamatory, degenerative, axial, ectatic condition of the cornea in which the cornea assumes an irregular conical shape. ^[1] Because corneal distortion is the reason behind the deterioration of visual function of patients affected by the condition, several surgical options are now available aiming to support ^[2] and reshaping or molding ^[3],[4] the cornea.

Corneal reshaping is a concept on which intrastromal rings are designed. ^[5] The use of incomplete intrastromal rings implantation has been proposed as an alternative option in the treatment of corneal ectasia. ^[3] The incomplete rings available on the market for many years are Intacs (Addition Technology, Inc.), Keraring (Mediphacos Ltd.), and Ferrara ring (Ferrara Ophthalmics Ltd.). ^[6],[7],[8]

The complete intrastromal ring, MyoRing (Dioptex, GmbH, Linz, Austria), is a new effective technique as reported by recent studies in the management of keratoconus. ^[5],[9] The technique uses a flexible, different size (diameter range; 5-8 mm and thickness range; 200-400 μm increments), complete ring shaped intracorneal implant which is inserted into a closed intracorneal pocket made with the pocket maker microkeratome (Dioptex, GmbH). The pocket maker microkeratome (which developed by Alio et al. in 2007) ^[5] consists of an ultrathin micron-guided diamond blade with extremely high cutting precision which exceeds that of a femtosecond laser, in particular if the cutting is performed in the deep cornea (≥300 μ). ^[9] The depth of the corneal pocket has been proposed earlier to be 300 μm under the surface of the cornea. Recently, Jabbarvand et al. (2014) found that an implantation of 250 μm has comparable outcomes with the previously applied 300 μm implantation depth.

Few studies were carried on the outcome of this new operation. Alio et al. (2011) implanted 12 eyes of corneal ectasia with MyoRing. Their study concluded that the new technology allows significant reduction of the high myopic errors because of the induced significant central flattening of the cornea.

The full ring procedure is not yet widely used in Sudan. This study aimed to highlight the great outcomes of the first patient who underwent this operation in this country.

Case report

In September 2013, an 18-year-old male patient with bilateral keratoconus was referred to our eye center for corneal transplant for his right eye. The patient was recruited for full ophthalmic examinations. According to Amsler-Krumeich classification, the patient was graded as stage 4 in the right eye and stage 3 in the left eye. ^[10]

Preoperative data

The uncorrected distance visual acuity (UCDVA) was 0.01 (<1.3 logMAR) in his right eye and 0.05 (1.3 logMAR) in his left eye. Patient's objective refraction was −12.00/−5.00 × 178 in the left eye and no reading was detected in the right eye. With −10.50/−2.00 × 180 and −11.00/−2.00 × 180 spectacle correction, patient's visual acuity improved only to 0.03 (<1.3 logMAR) and 0.7 (0.15 logMAR) in right and left eyes respectively. Advanced keratoconus was detected with the right eye more affected than the left eye. Slit-lamp biomicroscopic revealed apical scaring in patient's right eye. Other examinations included corneal topography and pachymetry were carried. Using SHIN-NIPPON corneal topographer (TOWA Medical Instruments Co Ltd., Japan), right eye showed steepest K reading and flattest K reading of 62.92D (5.36) at 98 and 56.23D (6.00) at 8 respectively. Examinations of the left eye showed steepest K reading of 56.20D (60.1) at 74 and flattest K reading of 51.18D (6.59) at 164. Central corneal thickness (CCT) was measured using Stratus OCT 3000 (Carl-Zeisss Meditec Inc., Germany). Examinations showed that the CCT of the right and left eyes were 426 μm and 421 μm, respectively.

Decision

We decided to implant the patient's left eye with MyoRing.

Implantation of MyoRing

The surgery was performed using the PocketMaker microkeratome (Dioptex, Austria) and the MyoRing intracorneal implant (Dioptex, GmbH, Austria) to be implanted into 9 mm diameter corneal pocket created at 280 μ depth. The size of the MyoRing implanted was 5 mm as suggested by the CISIS nomogram. ^[9],[11] [Table 1] shows the nomogram used to select the intracorneal continuous ring (ICCR).

Table 1: The CISIS nomogram

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After implantation

After 1-week from the operation, the patient attended for follow-up. Autorfractometer reading was found to be −6.00 DC × 180 in the operated eye. The UCDVA was 0.7 (0.15 logMAR), which improved one line (0.8, 0.1 logMAR) with −2.00 DC × 180 subjectively. Ophthalmic examinations indicated a stable eye condition with no severe side effects.

After 3 months, visual and refractive data, and pachymetry were evaluated with the same preoperative instruments. Patient's objective refraction was −1.00/−4.00 DC × 175 and UCDVA was 0.8 (0.1 logMAR). With −3.00 DC × 180 spectacle correction, patient's BCVA improved to 1.0 (0.0 Log MAR). In comparison to preoperative UCDVA and BCVA, the postoperative UCDVA was improved 12 lines (from 0.05 [1.3 logMAR] to 0.8 [0.1 logMAR]) and BCVA improved also 3 lines (from 0.67 [0.18 logMAR] to 1.0 [0.0 logMAR]).

[Figure 1] illustrates the pre- and post-operative topographic maps of the operated eye. The postoperative data showed significant reduction in corneal steepening. The flattest K reading reduced improved to 41.25D, while the steepest K reading improved to 45.13D. The mean K reading was then reduced to 43.19D. The improvement in mean K reading was calculated to be 10.51D. No significant changes were found between preoperative (421 μm) and postoperative (444 μm) pachymetry at the thinnest point of the cornea. [Table 2] shows the pre- and post-operative visual and refractive data.

Figure 1: Pre- and post-operative topographic maps of the operated eye

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Table 2: Pre- and post-operative data

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Discussion

Keratoconus is one of the most challenging corneal disorders. Changing the configuration of the cornea is an important issue in managing keratoconus and keratectasia. ^[11],[12] Intrastromal (incomplete) corneal ring segments and the modified complete intacorneal ring (MyoRing) implantations have been proposed to improve corneal irregularity, reduce the refractive error and then improve the visual outcomes of the keratoconic cornea. ^[12],[13]

Mahmood et al. 2010 reported that the outcome of complete intracorneal ring implantations as a treatment of keratoconus based directly on the selection of ring thickness, meridian, and centration. The MyoRing implanted for our case was followed the modified CISIS nomogram designed especially for the Middle East population. ^[14]

In agreement with other reports, ^[5],[8],[14] the result from the current study found that the UCDVA and BCVA improved significantly after 3 months of MyoRing implantation. This improvement could be attributed to the noticeable flattening of the central cornea of our patient.

Compared to immediate preoperative follow-up (1-week), in the 3 weeks follow-up visit, the eye showed a significant improvement in UCDVA and BCVA. This improvement in visual acuity during the first 3 months after ICCR implantation may be attributed to the adaptation with the MyoRing diameter. ^[11] This explanation corresponds well also with the observation that the patient reports of improvement in vision during the time.

References

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