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Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration
G Model CLAE 904 No. of Pages 5
Contact Lens and Anterior Eye xxx (2016) xxx–xxx
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Contact Lens and Anterior Eye journal homepage: www.elsevier.com/locate/clae
Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration Leyla Asena* , Dilek Dursun Altınörs Baskent University Faculty of Medicine, Department of Ophthalmology, Ankara, Turkey
A R T I C L E I N F O
A B S T R A C T
Article history: Received 28 February 2016 Received in revised form 20 June 2016 Accepted 29 June 2016
Purpose: To report the clinical outcomes of scleral Misa1 lenses (Microlens Contactlens Technolgy, Arnhem, Netherlands) for visual rehabilitation in patients with pellucid marginal degeneration (PMD). Mehods: In this prospective interventional case series, 24 eyes of 12 PMD patients were fitted with scleral Misa1 lenses. Patients were followed regularly for continuous daily wearing time (CDWT), contact lens handling issues, visual acuity, and any subjective or objective contact lens related complications. Results: The mean patient age was 35.0 13.8 years (range, 23–47 years). The average length of follow-up was 14.1 3.7 months (range, 8.5–18 months). All eyes were fit with mini Misa1 scleral lenses with a diameter of 16.5 or 17 mm. The mean Snellen best-corrected visual acuity (BCVA) before scleral lenses with spectacle correction was 0.42 0.15 (range, 0.2–0.6). With scleral lenses, mean BCVA was 0.75 0.15 (range, 0.5–0.9), (p = 0.003) with a mean gain of 3.3 lines of BCVA. More than half (16 eyes, 67%) reported wearing their scleral lenses for 8 h or more on a daily basis. Three patients (6 eyes, 25%) abandoned scleral lens wear. Patients who abandoned the scleral lens wear tended to have a better spectacle corrected visual acuity and less gain of lines. Conclusions: Scleral lenses can be used succesfully in patients with PMD who are intolerant to other types of contact lenses. Patients who have a low spectacle BCVA and a higher gain of visual acuity with scleral lenses are good candidates for scleral lens use. ã 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Keywords: Corneal ectasia Scleral contact lenses Pellucid marginal degeneration Visual rehabilitation
1. Introduction Pellucid marginal degeneration (PMD) is a rare, bilateral, asymmetric, ectatic disorder of the cornea most commonly associated with an arcuate band of thinning in the inferior peripheral cornea approximately 1 mm from the limbus [1–4]. The hallmarks of PMD are corneal topographical abnormalities above the thinned zone which show an obvious flattening of the cornea along the vertical meridian and “against-the-rule” astigmatism. There is an inferior peripheral steepening extending into the mid-peripheral, inferior oblique corneal meridians in a classic “crab-claw”, “butterfly” or “kissing doves” appearance. Corneal thinning usually occurs in the 4- to 8-o’clock position and can be severe. [4] The point of maximal protrusion occurs in the region of cornea just superior to the thinned region [1–4]. This is in contrast to the more common ectatic disorder, keratoconus, in which apical protrusion occurs within regions of thinned central and paracentral cornea [5].
* Corresponding author at: Baskent University Faculty of Medicine, Fevzi Çakmak Caddesi, 06490, Bahçelievler, Ankara, Turkey. E-mail address: [email protected] (L. Asena).
Many options exist for the treatment of early and moderate PMD. Most patients with PMD are treated non-surgically with spectacles or contact lenses [1,6–9]. Soft and hybrid contact lenses can be used in early PMD, but lose their effectiveness as the disease progresses [9–13]. In moderate PMD, the development of irregular astigmatism and progressive corneal irregularity often necessitates the use of large diameter rigid gas permeable lenses [6–9]. Specialized contact lenses such as reverse geometry lenses and “bi-toric” lenses have proven useful in the management of moderate PMD [14,15]. In advanced PMD, fitting with corneal lenses is extremely difficult due to the peripheral location of the ectasia. For the same reason, PMD patients are usually poor candidates for PK as the corneal thinning occurs close to the limbus. Large eccentric grafts are required and must be positioned very close to the limbus thus increasing the risk of graft rejection, suture-induced complications and corneal neovascularisation [16]. Therefore, the scleral contact lens (ScCL) is a usefull non-surgical treatment of last resort for PMD patients [17]. Scleral lenses are large-diameter gas-permeable lenses that completely vault the cornea and rest on the sclera. In recent years, there have been a variety of studies reporting the success of scleral
http://dx.doi.org/10.1016/j.clae.2016.06.010 1367-0484/ã 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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lenses in the treatment of ocular surface conditions, postkeratoplasty patients and ectatic disorders including a very recent study evaluating the succes of PROSE (prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sightight, USA) in PMD patients [17–21]. However, to the best of our knowledge, there have been no reports evaluating the use of scleral Misa1 lenses (Microlens Contactlens Technolgy, Arnhem, Netherlands) in PMD patients, reporting clinical outcomes in long term follow-up. The aim in the current study was to report the clinical outcomes and complications of scleral Misa1 lenses for visual rehabilitation in patients with PMD. 2. Materials and methods In this prospective interventional case series, 24 eyes of 12 (7 male, 5 female) PMD patients who had neither acceptable visual acuity with spectacles, nor could be fitted with corneal RGP lenses referred to Baskent University Faculty of Medicine, Department of Ophthalmology were fitted with scleral Misa1 lenses. The study was approved by the Ethics Committee of Baskent University Faculty of Medicine. Corneal topography was performed by Scheimpflug imaging (WaveLight Allegro Oculyzer TM (WaveLight AG, Erlangen, Germany)) which is a diagnostic device based on the Pentacam HR technology. Detailed anterior and posterior elevation maps, anterior curvature topography with indices, and full pachymetry maps with 12 mm of corneal coverage and thickness data were examined for the accurate diagnosis of PMD, according to recommendations by Belin et al. [22] The parameters of the trial set were as follows: – Misa1 lens (Microlens Contactlens Technolgy, Arnhem, Netherlands) trial set including 20 lenses (4 full Misa, 10 mini Misa, 6 non-rotationally symmetric lenses; diameter: 16.5– 17 mm for mini Misa, 20 mm for full Misa; power 2.00 D for all lenses. – Sagittal vault: 325–400 mm for mini Misa and 400–500 mm for full Misa. – Base curve: 7.8, 8.3 and 8.8 mm for mini Misa and 7.8 mm for full Misa. – Scleral aperture diameter: 13 mm (Normal) and 13.5 mm (Wide). – Scleral curve: Standard 13.5 mm for mini and full Misa, alternative non-rotationally symmetric lenses for patients with scleral toricity with 0.75 mm difference for mini Misa and with 0.50, 1.00 mm differences for full Misa. – Material: Fluorosilicone acrylate with hydrophilic monomers, DK: 122. The patients had neither acceptable visual acuity with spectacles, nor could be fitted with corneal RGP lenses (diameter ranging from 9.30 to 11 mm). The fit of the scleral lens was assessed by a single experienced contact lens practitioner in this field after 5 min and again after at least 30 min of wearing. The fit was evaluated as: Ideal: No touch over the entire cornea in the fluorescein pattern viewed under a cobalt light, evaluated by a 30 oblique slit lamp beam (from the midline), vaulting approximately 250 mm over the central cornea by subjective slit illumination (Fig. 1), landing zone outside the limbal area, no impingement over conjunctival vessels. Acceptable: No corneal touch by subjective slit illumination and minimal (less than 3 clock hours) conjunctival impingement. Unacceptable: Corneal touch by subjective slit illumination with maximum available sagittal vault and/or more than 3 clock hours conjunctival impingement.
Fig. 1. Anterior segment photograph of a patient fitted with a scleral Misa lens. The fit was evaluated as ideal with no touch over the entire cornea by a 30 oblique slit lamp beam, vaulting approximately 250 mm over the central cornea by subjective slit illumination, landing zone outside the limbal area, no impingement over conjunctival vessels.
The patients with either ideal or acceptable fit were allowed to use the lenses for at least 1 h and were then inquired about subjective satisfaction. Then, the lens was prescribed for the patients with either ideal or acceptable fit. Patients were instructed to take brief breaks every 4–5 h of continuous wear, to replenish the lens with fresh unpreserved saline. The patients who started wearing their lenses were followed regularly for daily scleral lens wear time, contact lens handling issues, visual acuity, and any subjective or objective contact lens related complications. Characteristics of patients who continued or discontinued their scleral lens wear at the last visit were compared using the Mann Whitney-U test. 3. Results The mean age of the patients was 35.0 13.8 years (range, 23–47 years). The average length of follow-up was 14.1 3.7 months (range, 8.5–18 months). All eyes had been earlier fit unsuccessfully with other types of contact lenses, and the patients were either clinically intolerant of the other lenses or were subjectively unhappy with them. Eight eyes (33%) had been fit with more than one type of contact lens before being fit with a scleral lens. Twenty four eyes had previously been fit with RGP contact lenses, 2 eyes had been fit with hybrid lenses. None of the patients had previously worn any other types of scleral lenses. The mean Kmax was 53.9 4.9 D (range, 46.6–57.1 D) and all eyes had a clear cornea. All eyes were fit with mini Misa1 scleral lenses and fitting with a full Misa1 scleral lens was not needed in any of the cases. Eighteen eyes (75%) were fit with a scleral lens of 16.5 mm diameter and 6 eyes (25%) with a scleral lens of 17 mm diameter. The choice of total diameter was determined by the choice of scleral aperture diameter (normal in 18 eyes and wide in 6 eyes). Sagittal vault parameter of the fitted lens was 350 mm in 10 eyes (42%), 375 mm in 6 eyes (25%) and 400 mm in 8 eyes (33%). The base curve was 7.8 mm in 14 eyes (58%), 8.3 mm in 6 eyes (25%) and 8.8 mm in 4 eyes (17%). Non-rotationally symmetric lenses with 0.75 mm difference were used for 6 eyes (25%) with prominent scleral toricity. Fig. 2 shows the anterior segment image (Fig. 2A) and topography (Fig. 2B) of a patient who was fit with a mini Misa lens which has a base curve of 7.8 mm, diameter of 16.5 mm and vault hight of 375 mm. The fit was evaluated as ideal. The mean Snellen best-corrected visual acuity (BCVA) before scleral lenses with spectacle correction or refraction was 0.42 0.15 (range, 0.2–0.6). With scleral lenses, mean BCVA was 0.75 0.15 (range, 0.5–0.9), (p = 0.003, paired samplest test) with a mean gain of 3.3 lines. With scleral lenses, 12 eyes (50%) achieved a BCVA of 0.8 or better. All eyes experienced improvement in BCVA with scleral lenses compared with spectacle refraction. The mean continuous lens-wear time per day was 7.6 2.9 h (range; 2–14 h). More than half (16 eyes, 67%) reported wearing
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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Fig. 2. The anterior segment image (Fig. 2A) and topography (Fig. 2B) of a patient who was fit with a mini Misa lens which has a base curve of 7.8 mm, diameter of 16.5 mm and vault hight of 375 mm. The fit was evaluated as ideal.
Fig. 3. The distribution of the patients according to the daily continuous wearing time of their scleral lenses.
their scleral lenses for 8 h or more and one fourth (6 eyes, 25%) reported wearing their scleral lenses for 4 h or less on a daily basis (Fig. 3). Subjective complaints associated with scleral lenses including discomfort, difficulty with lens insertion and/or removal and suboptimal quality of vision were reported by 4 patients (7 eyes, 29%). Three patients (6 eyes), representing 25% of all cases, abandoned scleral lens wear. The most common reason for discontinuation of lens wear was difficulty with scleral lens insertion or removal (4 eyes, 17%). (Table 1). Different characteristics of patients who continued to wear their scleral lenses in the last visit, and who discontinued scleral lens wear, are given in Table 2. There was no significant difference between patients who abandoned and continued scleral lens wear in terms of age, visual acuity with scleral lenses and Kmax. However, patients who abandoned the scleral lens wear tended to have a better spectacle corrected visual acuity and lower gain of lines with scleral lenses. No complications related to scleral lens use were observed in any of the patients.
increased awareness and acceptance of scleral lenses by ophthalmologists worlwide. Scleral lenses are particularly useful in situations where corneal RGP lenses are unstable and soft lenses are inadequate for correction of irregular astigmatism. These lenses demonstrated therapeutic potential in their ability to successfully fit most patients with distorted corneas that were intolerant to other forms of vision correction including piggyback, hybrid or corneal gas permeable lenses [23]. Tan et al. showed that 69% of their 517 eyes fitted with scleral lenses had previously failed with other contact lenses [24]. Most of these patients would probably have been referred for a corneal transplant. Several reports show the potential of scleral lenses to delay or prevent surgery [25–27], which has an important impact on the costs involved in the health care of these patients [28]. Similarly, in the current study, all patients were either clinically intolerant of the previously fitted lenses or were subjectively unhappy with them.
Table 1 Reasons for discontinuation of the scleral lens wear.
4. Discussion
Reason for discontinuation
Number of patients
%
The technological advances in scleral lens designs over the past years and clinical appreciation of their therapeutic value, led to
Difficulty with lens insertion and/or removal Visual dissatisfaction Discomfort
4 1 1
17 4 4
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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Table 2 Characteristics of patients who continued to wear their scleral lenses in the last visit, and who discontinued their scleral lens wear.
Mean age Mean spectacle corrected Snellen BCVA Mean Snellen BCVA with scleral lenses Mean gain in visual acuity (lines) Kmax (D)
Discontinuation
Continuation
P value
36.2 0.52 0.68 1.6 53.2
34.3 0.34 0.72 3.8 53.4
0.08 0.03 0.42 0.02 0.84
Eight eyes (33%) had been fit with more than one type of contact lens before being fit with a scleral lens. A successful fit with scleral lenses delayed or prevented surgery in these patients. The success with ScCL fitting is quite variable and may be difficult to define. When lenses are prescribed to correct irregular corneas, increasing visual acuity is the primary goal. In this regard, several studies report significant increases in visual acuity with ScCL fitting. Pullum et al. [29], in one of the largest studies reported on ScCL, reported a visual acuity of 6/9 or better in 78.7% of their patients fitted with ScCLs for ectatic and post-surgical irregular corneas. Visser et al. [30] reported a visual acuity of 0.8 in 62.9%, 0.6–0.8 in 17.8% and 0.4–0.6 in 10.8% of the patients with Visser bitangential scleral lenses, in a large cohort including keratoconus, ocular surface disease and post penetrating keratoplasty patients. Baran et al. [31] reported the outcome of PROSE treatment of corneal ectasia including patients with keratoconus (49 patients), PMD (3 patients) and post refractive surgery ectasia (7 patients). The visual acuity increased from a baseline of 20/70 to 20/40 in 93% of the patients, indicating an increase of 3 or more lines. In another study by Pecego et al. [23] including 107 patients with keratoconus, high post-keratoplasty astigmatism and corneal scarring, the improvement in BCVA compared with previous contact lens or glasses correction was a mean gain of 3.5 Snellen lines with Jupiter scleral lenses (Visionary Optics). Similarly, we observed that, the Snellen BCVA increased from 0.42 to 0.75 with a mean gain of 3.3 lines and 50% of the eyes achieved a BCVA of 0.8 or better, in patients with PMD. Another parameter to report success is the daily continuous wearing time of the scleral lenses. Most of the studies report wearing times between 8 and 16 h/day, although some report shorter times for some patients [32]. In the study by Kok and Visser [33], 83% of the 50 eyes with multiple diagnoses were able to wear the scleral CL for more than 8 h including brief removal of the lenses for cleaning. Pullum et al. [29] found an average of 10 h or more wearing time in 59% (n = 538) of their patients. A previous study by the same group reported a mean wearing time of 16.2 h (range, 3–18 h) with a follow-up period of 17 months [25]. However, this study included patients fitted with a variety of indications and not only visual rehabilitation. In a more recent study evaluating the clinical performance with scleral contact lenses for patients with irregular astigmatism, the mean lens-wear time per day of the scleral lens was 10.5 h/day (range, 2–18 h), 65% had a wearing time of 10 h/day or more, and 73% had a wearing time of 8 h/day or more [34]. In our study, the mean continuous lens-wear time per day was 7.6 2.9 h (range; 2–14 h), which is slightly shorter than the previously reported continuous wearing times. However, 67% of the patients reported wearing their scleral lenses for 8 h or more on a daily basis, which is quite similar with previous reports evaluating the succes of ScCL in patients with irregular corneas. Discontinuation of scleral lens wear is an important indication of an unsuccessful fit. The rate of scleral lens discontinuation reported in the literature ranges from 19% to 29% [18,20,29,34]. Pullum and Buckley [20] had reported an approximate 24% failure rate in a cohort of postkeratoplasty patients. Tan et al. [18] reported a 29% failure rate in a cohort of 343 patients including keratoconus,
aphakia, postpenetrating keratoplasty, irregular astigmatism and ocular surface disorders. Ortenberg et al. [34] found that 27% discontinued scleral lens wear in a cohort with multiple diagnoses including keratoconus, postpenetrating keratoplasty, keratoglobus, PMD and iatrogenic ectasia. Severinsky et al. [35] reported the lowest failure rate of 19.4% and recently Barnett et al. [36] reported the highest discontinuation rate of 35.4%, both in their groups of postkeratoplasty patients. They associated the high rate of discontinuation with the relatively high mean patient age in their study. In our study, 25% of the patients abandoned ScCL wear, which is similar to the results of the previous reports. The most common reason for discontinuation of lens wear reported by the patients was difficulty with scleral lens insertion or removal (17%), followed by visual dissatisfaction (4%) and discomfort (4%). One would expect that there would be a relatively greater part of the population fitted with base curve 8.80 in order to avoid bearing on the inferior periphery. However only 4 eyes (17%) in our study population were fitted with a base curve of 8.80. This may be due to the relatively low number of patients with extreme inferior corneal steepening in our study population where the mean Kmax was 53.9 4.9 D (range, 46.6–57.1 D). This may also be the reason why most patients in our study did well with a regular prolate design. When fitting the highest elevation point of the cornea results in excessive central clearance, oblate desingns, which are also offered by the Misa1 system, can be used. Excessive central clearance may cause lower oxygen transmission to the cornea and higher incidence of fogging/debri accumulation which is a common problem with scleral lenses. This problem may be overcome by the use of scleral lenses with an oblate design which are usefull in patients with a flatter central curve and steeper limbus/midperiphery such as after refractive surgery, implantation of intracorneal ring segments and corneal transplants with high graft junctions. When fitting patients with PMD, special care must be taken to prevent bearing at the steep lower meridian and excessive clearance at the flatt upper meridian of the cornea. Higher diameter scleral lenses with a flatter base curve and oblate designs can be usefull in severe cases. As a result, scleral contact lenses with a diameter of 16.5 mm or 17 mm could be used successfully in the rehabilitation of PMD patients who were intolerant to any other types of contact lenses. This shows that scleral lenses are an important alternative for correction of high or irregular astigmatism in patients with PMD. Our results support the ability to improve visual acuity in these challenging patients that have failed any other optical modalities for visual rehabilitation. In our opinion, scleral contact lenses can minimise problems in contact lens fitting and can improve the tolerance and the visual results. We recommend this procedure, especially for moderate or advanced PMD who could not be fitted with other types of contact lenses, in cases of poor operative prognosis and for patients who refuse further surgical interventions. Conflicts of interest There are no other conflicts of interest nor sources of funding for this study.
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
Contact Lens and Anterior Eye xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Contact Lens and Anterior Eye journal homepage: www.elsevier.com/locate/clae
Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration Leyla Asena* , Dilek Dursun Altınörs Baskent University Faculty of Medicine, Department of Ophthalmology, Ankara, Turkey
A R T I C L E I N F O
A B S T R A C T
Article history: Received 28 February 2016 Received in revised form 20 June 2016 Accepted 29 June 2016
Purpose: To report the clinical outcomes of scleral Misa1 lenses (Microlens Contactlens Technolgy, Arnhem, Netherlands) for visual rehabilitation in patients with pellucid marginal degeneration (PMD). Mehods: In this prospective interventional case series, 24 eyes of 12 PMD patients were fitted with scleral Misa1 lenses. Patients were followed regularly for continuous daily wearing time (CDWT), contact lens handling issues, visual acuity, and any subjective or objective contact lens related complications. Results: The mean patient age was 35.0 13.8 years (range, 23–47 years). The average length of follow-up was 14.1 3.7 months (range, 8.5–18 months). All eyes were fit with mini Misa1 scleral lenses with a diameter of 16.5 or 17 mm. The mean Snellen best-corrected visual acuity (BCVA) before scleral lenses with spectacle correction was 0.42 0.15 (range, 0.2–0.6). With scleral lenses, mean BCVA was 0.75 0.15 (range, 0.5–0.9), (p = 0.003) with a mean gain of 3.3 lines of BCVA. More than half (16 eyes, 67%) reported wearing their scleral lenses for 8 h or more on a daily basis. Three patients (6 eyes, 25%) abandoned scleral lens wear. Patients who abandoned the scleral lens wear tended to have a better spectacle corrected visual acuity and less gain of lines. Conclusions: Scleral lenses can be used succesfully in patients with PMD who are intolerant to other types of contact lenses. Patients who have a low spectacle BCVA and a higher gain of visual acuity with scleral lenses are good candidates for scleral lens use. ã 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Keywords: Corneal ectasia Scleral contact lenses Pellucid marginal degeneration Visual rehabilitation
1. Introduction Pellucid marginal degeneration (PMD) is a rare, bilateral, asymmetric, ectatic disorder of the cornea most commonly associated with an arcuate band of thinning in the inferior peripheral cornea approximately 1 mm from the limbus [1–4]. The hallmarks of PMD are corneal topographical abnormalities above the thinned zone which show an obvious flattening of the cornea along the vertical meridian and “against-the-rule” astigmatism. There is an inferior peripheral steepening extending into the mid-peripheral, inferior oblique corneal meridians in a classic “crab-claw”, “butterfly” or “kissing doves” appearance. Corneal thinning usually occurs in the 4- to 8-o’clock position and can be severe. [4] The point of maximal protrusion occurs in the region of cornea just superior to the thinned region [1–4]. This is in contrast to the more common ectatic disorder, keratoconus, in which apical protrusion occurs within regions of thinned central and paracentral cornea [5].
* Corresponding author at: Baskent University Faculty of Medicine, Fevzi Çakmak Caddesi, 06490, Bahçelievler, Ankara, Turkey. E-mail address: [email protected] (L. Asena).
Many options exist for the treatment of early and moderate PMD. Most patients with PMD are treated non-surgically with spectacles or contact lenses [1,6–9]. Soft and hybrid contact lenses can be used in early PMD, but lose their effectiveness as the disease progresses [9–13]. In moderate PMD, the development of irregular astigmatism and progressive corneal irregularity often necessitates the use of large diameter rigid gas permeable lenses [6–9]. Specialized contact lenses such as reverse geometry lenses and “bi-toric” lenses have proven useful in the management of moderate PMD [14,15]. In advanced PMD, fitting with corneal lenses is extremely difficult due to the peripheral location of the ectasia. For the same reason, PMD patients are usually poor candidates for PK as the corneal thinning occurs close to the limbus. Large eccentric grafts are required and must be positioned very close to the limbus thus increasing the risk of graft rejection, suture-induced complications and corneal neovascularisation [16]. Therefore, the scleral contact lens (ScCL) is a usefull non-surgical treatment of last resort for PMD patients [17]. Scleral lenses are large-diameter gas-permeable lenses that completely vault the cornea and rest on the sclera. In recent years, there have been a variety of studies reporting the success of scleral
http://dx.doi.org/10.1016/j.clae.2016.06.010 1367-0484/ã 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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lenses in the treatment of ocular surface conditions, postkeratoplasty patients and ectatic disorders including a very recent study evaluating the succes of PROSE (prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sightight, USA) in PMD patients [17–21]. However, to the best of our knowledge, there have been no reports evaluating the use of scleral Misa1 lenses (Microlens Contactlens Technolgy, Arnhem, Netherlands) in PMD patients, reporting clinical outcomes in long term follow-up. The aim in the current study was to report the clinical outcomes and complications of scleral Misa1 lenses for visual rehabilitation in patients with PMD. 2. Materials and methods In this prospective interventional case series, 24 eyes of 12 (7 male, 5 female) PMD patients who had neither acceptable visual acuity with spectacles, nor could be fitted with corneal RGP lenses referred to Baskent University Faculty of Medicine, Department of Ophthalmology were fitted with scleral Misa1 lenses. The study was approved by the Ethics Committee of Baskent University Faculty of Medicine. Corneal topography was performed by Scheimpflug imaging (WaveLight Allegro Oculyzer TM (WaveLight AG, Erlangen, Germany)) which is a diagnostic device based on the Pentacam HR technology. Detailed anterior and posterior elevation maps, anterior curvature topography with indices, and full pachymetry maps with 12 mm of corneal coverage and thickness data were examined for the accurate diagnosis of PMD, according to recommendations by Belin et al. [22] The parameters of the trial set were as follows: – Misa1 lens (Microlens Contactlens Technolgy, Arnhem, Netherlands) trial set including 20 lenses (4 full Misa, 10 mini Misa, 6 non-rotationally symmetric lenses; diameter: 16.5– 17 mm for mini Misa, 20 mm for full Misa; power 2.00 D for all lenses. – Sagittal vault: 325–400 mm for mini Misa and 400–500 mm for full Misa. – Base curve: 7.8, 8.3 and 8.8 mm for mini Misa and 7.8 mm for full Misa. – Scleral aperture diameter: 13 mm (Normal) and 13.5 mm (Wide). – Scleral curve: Standard 13.5 mm for mini and full Misa, alternative non-rotationally symmetric lenses for patients with scleral toricity with 0.75 mm difference for mini Misa and with 0.50, 1.00 mm differences for full Misa. – Material: Fluorosilicone acrylate with hydrophilic monomers, DK: 122. The patients had neither acceptable visual acuity with spectacles, nor could be fitted with corneal RGP lenses (diameter ranging from 9.30 to 11 mm). The fit of the scleral lens was assessed by a single experienced contact lens practitioner in this field after 5 min and again after at least 30 min of wearing. The fit was evaluated as: Ideal: No touch over the entire cornea in the fluorescein pattern viewed under a cobalt light, evaluated by a 30 oblique slit lamp beam (from the midline), vaulting approximately 250 mm over the central cornea by subjective slit illumination (Fig. 1), landing zone outside the limbal area, no impingement over conjunctival vessels. Acceptable: No corneal touch by subjective slit illumination and minimal (less than 3 clock hours) conjunctival impingement. Unacceptable: Corneal touch by subjective slit illumination with maximum available sagittal vault and/or more than 3 clock hours conjunctival impingement.
Fig. 1. Anterior segment photograph of a patient fitted with a scleral Misa lens. The fit was evaluated as ideal with no touch over the entire cornea by a 30 oblique slit lamp beam, vaulting approximately 250 mm over the central cornea by subjective slit illumination, landing zone outside the limbal area, no impingement over conjunctival vessels.
The patients with either ideal or acceptable fit were allowed to use the lenses for at least 1 h and were then inquired about subjective satisfaction. Then, the lens was prescribed for the patients with either ideal or acceptable fit. Patients were instructed to take brief breaks every 4–5 h of continuous wear, to replenish the lens with fresh unpreserved saline. The patients who started wearing their lenses were followed regularly for daily scleral lens wear time, contact lens handling issues, visual acuity, and any subjective or objective contact lens related complications. Characteristics of patients who continued or discontinued their scleral lens wear at the last visit were compared using the Mann Whitney-U test. 3. Results The mean age of the patients was 35.0 13.8 years (range, 23–47 years). The average length of follow-up was 14.1 3.7 months (range, 8.5–18 months). All eyes had been earlier fit unsuccessfully with other types of contact lenses, and the patients were either clinically intolerant of the other lenses or were subjectively unhappy with them. Eight eyes (33%) had been fit with more than one type of contact lens before being fit with a scleral lens. Twenty four eyes had previously been fit with RGP contact lenses, 2 eyes had been fit with hybrid lenses. None of the patients had previously worn any other types of scleral lenses. The mean Kmax was 53.9 4.9 D (range, 46.6–57.1 D) and all eyes had a clear cornea. All eyes were fit with mini Misa1 scleral lenses and fitting with a full Misa1 scleral lens was not needed in any of the cases. Eighteen eyes (75%) were fit with a scleral lens of 16.5 mm diameter and 6 eyes (25%) with a scleral lens of 17 mm diameter. The choice of total diameter was determined by the choice of scleral aperture diameter (normal in 18 eyes and wide in 6 eyes). Sagittal vault parameter of the fitted lens was 350 mm in 10 eyes (42%), 375 mm in 6 eyes (25%) and 400 mm in 8 eyes (33%). The base curve was 7.8 mm in 14 eyes (58%), 8.3 mm in 6 eyes (25%) and 8.8 mm in 4 eyes (17%). Non-rotationally symmetric lenses with 0.75 mm difference were used for 6 eyes (25%) with prominent scleral toricity. Fig. 2 shows the anterior segment image (Fig. 2A) and topography (Fig. 2B) of a patient who was fit with a mini Misa lens which has a base curve of 7.8 mm, diameter of 16.5 mm and vault hight of 375 mm. The fit was evaluated as ideal. The mean Snellen best-corrected visual acuity (BCVA) before scleral lenses with spectacle correction or refraction was 0.42 0.15 (range, 0.2–0.6). With scleral lenses, mean BCVA was 0.75 0.15 (range, 0.5–0.9), (p = 0.003, paired samplest test) with a mean gain of 3.3 lines. With scleral lenses, 12 eyes (50%) achieved a BCVA of 0.8 or better. All eyes experienced improvement in BCVA with scleral lenses compared with spectacle refraction. The mean continuous lens-wear time per day was 7.6 2.9 h (range; 2–14 h). More than half (16 eyes, 67%) reported wearing
Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010
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Fig. 2. The anterior segment image (Fig. 2A) and topography (Fig. 2B) of a patient who was fit with a mini Misa lens which has a base curve of 7.8 mm, diameter of 16.5 mm and vault hight of 375 mm. The fit was evaluated as ideal.
Fig. 3. The distribution of the patients according to the daily continuous wearing time of their scleral lenses.
their scleral lenses for 8 h or more and one fourth (6 eyes, 25%) reported wearing their scleral lenses for 4 h or less on a daily basis (Fig. 3). Subjective complaints associated with scleral lenses including discomfort, difficulty with lens insertion and/or removal and suboptimal quality of vision were reported by 4 patients (7 eyes, 29%). Three patients (6 eyes), representing 25% of all cases, abandoned scleral lens wear. The most common reason for discontinuation of lens wear was difficulty with scleral lens insertion or removal (4 eyes, 17%). (Table 1). Different characteristics of patients who continued to wear their scleral lenses in the last visit, and who discontinued scleral lens wear, are given in Table 2. There was no significant difference between patients who abandoned and continued scleral lens wear in terms of age, visual acuity with scleral lenses and Kmax. However, patients who abandoned the scleral lens wear tended to have a better spectacle corrected visual acuity and lower gain of lines with scleral lenses. No complications related to scleral lens use were observed in any of the patients.
increased awareness and acceptance of scleral lenses by ophthalmologists worlwide. Scleral lenses are particularly useful in situations where corneal RGP lenses are unstable and soft lenses are inadequate for correction of irregular astigmatism. These lenses demonstrated therapeutic potential in their ability to successfully fit most patients with distorted corneas that were intolerant to other forms of vision correction including piggyback, hybrid or corneal gas permeable lenses [23]. Tan et al. showed that 69% of their 517 eyes fitted with scleral lenses had previously failed with other contact lenses [24]. Most of these patients would probably have been referred for a corneal transplant. Several reports show the potential of scleral lenses to delay or prevent surgery [25–27], which has an important impact on the costs involved in the health care of these patients [28]. Similarly, in the current study, all patients were either clinically intolerant of the previously fitted lenses or were subjectively unhappy with them.
Table 1 Reasons for discontinuation of the scleral lens wear.
4. Discussion
Reason for discontinuation
Number of patients
%
The technological advances in scleral lens designs over the past years and clinical appreciation of their therapeutic value, led to
Difficulty with lens insertion and/or removal Visual dissatisfaction Discomfort
4 1 1
17 4 4
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Table 2 Characteristics of patients who continued to wear their scleral lenses in the last visit, and who discontinued their scleral lens wear.
Mean age Mean spectacle corrected Snellen BCVA Mean Snellen BCVA with scleral lenses Mean gain in visual acuity (lines) Kmax (D)
Discontinuation
Continuation
P value
36.2 0.52 0.68 1.6 53.2
34.3 0.34 0.72 3.8 53.4
0.08 0.03 0.42 0.02 0.84
Eight eyes (33%) had been fit with more than one type of contact lens before being fit with a scleral lens. A successful fit with scleral lenses delayed or prevented surgery in these patients. The success with ScCL fitting is quite variable and may be difficult to define. When lenses are prescribed to correct irregular corneas, increasing visual acuity is the primary goal. In this regard, several studies report significant increases in visual acuity with ScCL fitting. Pullum et al. [29], in one of the largest studies reported on ScCL, reported a visual acuity of 6/9 or better in 78.7% of their patients fitted with ScCLs for ectatic and post-surgical irregular corneas. Visser et al. [30] reported a visual acuity of 0.8 in 62.9%, 0.6–0.8 in 17.8% and 0.4–0.6 in 10.8% of the patients with Visser bitangential scleral lenses, in a large cohort including keratoconus, ocular surface disease and post penetrating keratoplasty patients. Baran et al. [31] reported the outcome of PROSE treatment of corneal ectasia including patients with keratoconus (49 patients), PMD (3 patients) and post refractive surgery ectasia (7 patients). The visual acuity increased from a baseline of 20/70 to 20/40 in 93% of the patients, indicating an increase of 3 or more lines. In another study by Pecego et al. [23] including 107 patients with keratoconus, high post-keratoplasty astigmatism and corneal scarring, the improvement in BCVA compared with previous contact lens or glasses correction was a mean gain of 3.5 Snellen lines with Jupiter scleral lenses (Visionary Optics). Similarly, we observed that, the Snellen BCVA increased from 0.42 to 0.75 with a mean gain of 3.3 lines and 50% of the eyes achieved a BCVA of 0.8 or better, in patients with PMD. Another parameter to report success is the daily continuous wearing time of the scleral lenses. Most of the studies report wearing times between 8 and 16 h/day, although some report shorter times for some patients [32]. In the study by Kok and Visser [33], 83% of the 50 eyes with multiple diagnoses were able to wear the scleral CL for more than 8 h including brief removal of the lenses for cleaning. Pullum et al. [29] found an average of 10 h or more wearing time in 59% (n = 538) of their patients. A previous study by the same group reported a mean wearing time of 16.2 h (range, 3–18 h) with a follow-up period of 17 months [25]. However, this study included patients fitted with a variety of indications and not only visual rehabilitation. In a more recent study evaluating the clinical performance with scleral contact lenses for patients with irregular astigmatism, the mean lens-wear time per day of the scleral lens was 10.5 h/day (range, 2–18 h), 65% had a wearing time of 10 h/day or more, and 73% had a wearing time of 8 h/day or more [34]. In our study, the mean continuous lens-wear time per day was 7.6 2.9 h (range; 2–14 h), which is slightly shorter than the previously reported continuous wearing times. However, 67% of the patients reported wearing their scleral lenses for 8 h or more on a daily basis, which is quite similar with previous reports evaluating the succes of ScCL in patients with irregular corneas. Discontinuation of scleral lens wear is an important indication of an unsuccessful fit. The rate of scleral lens discontinuation reported in the literature ranges from 19% to 29% [18,20,29,34]. Pullum and Buckley [20] had reported an approximate 24% failure rate in a cohort of postkeratoplasty patients. Tan et al. [18] reported a 29% failure rate in a cohort of 343 patients including keratoconus,
aphakia, postpenetrating keratoplasty, irregular astigmatism and ocular surface disorders. Ortenberg et al. [34] found that 27% discontinued scleral lens wear in a cohort with multiple diagnoses including keratoconus, postpenetrating keratoplasty, keratoglobus, PMD and iatrogenic ectasia. Severinsky et al. [35] reported the lowest failure rate of 19.4% and recently Barnett et al. [36] reported the highest discontinuation rate of 35.4%, both in their groups of postkeratoplasty patients. They associated the high rate of discontinuation with the relatively high mean patient age in their study. In our study, 25% of the patients abandoned ScCL wear, which is similar to the results of the previous reports. The most common reason for discontinuation of lens wear reported by the patients was difficulty with scleral lens insertion or removal (17%), followed by visual dissatisfaction (4%) and discomfort (4%). One would expect that there would be a relatively greater part of the population fitted with base curve 8.80 in order to avoid bearing on the inferior periphery. However only 4 eyes (17%) in our study population were fitted with a base curve of 8.80. This may be due to the relatively low number of patients with extreme inferior corneal steepening in our study population where the mean Kmax was 53.9 4.9 D (range, 46.6–57.1 D). This may also be the reason why most patients in our study did well with a regular prolate design. When fitting the highest elevation point of the cornea results in excessive central clearance, oblate desingns, which are also offered by the Misa1 system, can be used. Excessive central clearance may cause lower oxygen transmission to the cornea and higher incidence of fogging/debri accumulation which is a common problem with scleral lenses. This problem may be overcome by the use of scleral lenses with an oblate design which are usefull in patients with a flatter central curve and steeper limbus/midperiphery such as after refractive surgery, implantation of intracorneal ring segments and corneal transplants with high graft junctions. When fitting patients with PMD, special care must be taken to prevent bearing at the steep lower meridian and excessive clearance at the flatt upper meridian of the cornea. Higher diameter scleral lenses with a flatter base curve and oblate designs can be usefull in severe cases. As a result, scleral contact lenses with a diameter of 16.5 mm or 17 mm could be used successfully in the rehabilitation of PMD patients who were intolerant to any other types of contact lenses. This shows that scleral lenses are an important alternative for correction of high or irregular astigmatism in patients with PMD. Our results support the ability to improve visual acuity in these challenging patients that have failed any other optical modalities for visual rehabilitation. In our opinion, scleral contact lenses can minimise problems in contact lens fitting and can improve the tolerance and the visual results. We recommend this procedure, especially for moderate or advanced PMD who could not be fitted with other types of contact lenses, in cases of poor operative prognosis and for patients who refuse further surgical interventions. Conflicts of interest There are no other conflicts of interest nor sources of funding for this study.
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Please cite this article in press as: L. Asena, D.D. Altınörs, Clinical outcomes of scleral Misa lenses for visual rehabilitation in patients with pellucid marginal degeneration, Contact Lens & Anterior Eye (2016), http://dx.doi.org/10.1016/j.clae.2016.06.010