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 Table of Contents  
CASE REPORT
Year : 2023  |  Volume : 3  |  Issue : 2  |  Page : 298-301

Fitting pearls of scleral contact lenses in keratoglobus


1 Contact Lens Department, KVC Campus, L V Prasad Eye Institute, Vijayawada, Andhra Pradesh, India
2 Cornea and Anterior Segment Services, KVC Campus, L V Prasad Eye Institute, Vijayawada, Andhra Pradesh, India
3 Bausch and Lomb Contact Lens Centre, L V Prasad Eye Institute, Hyderabad, Telangana, India

Date of Submission22-Aug-2022
Date of Acceptance07-Dec-2022
Date of Web Publication28-Apr-2023

Correspondence Address:
Sushank Ashok Bhalerao
The Cornea Institute, Kode Venkatadri Chowdary (KVC) Campus, L V Prasad Eye Institute (LVPEI), Vijayawada - 521 134, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_2098_22

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  Abstract 


Keratoglobus is a rare noninflammatory corneal thinning disorder characterized by generalized thinning and globular protrusion of the cornea. Clinical presentation is characterized by progressive diminution resulting from irregular corneal topography with increased corneal fragility due to extreme thinning. Optical management usually involves in the form of spectacles or contact lenses. Contact lenses provide adequate vision for ectatic cornea without compromising the ocular health. Our case series discusses about the importance of the scleral lens modifications in improving vision as well as preventing corneal hydrops induced by scleral lenses.

Keywords: Contact lens, corneal hydrops, keratoglobus, ocular health, scleral lens


How to cite this article:
Prabhu M, Bhalerao SA, Chatterjee S, Vuyyuru S. Fitting pearls of scleral contact lenses in keratoglobus. Indian J Ophthalmol Case Rep 2023;3:298-301

How to cite this URL:
Prabhu M, Bhalerao SA, Chatterjee S, Vuyyuru S. Fitting pearls of scleral contact lenses in keratoglobus. Indian J Ophthalmol Case Rep [serial online] 2023 [cited 2023 Jun 4];3:298-301. Available from: https://www.ijoreports.in/text.asp?2023/3/2/298/374932



Corneal ectatic conditions can be well managed with spectacles. As the condition progresses, irregular astigmatism increases; for this, rigid corneal gas-permeable (RGP) lenses will be the best option. Several articles have discussed the fitting aspects of RGP contact lenses in different ectatic cornea.[1],[2],[3] Scleral contact lenses are very useful for patients who were RGP failures either because of inability to get an acceptable fit with regular RGP lenses or were contact lens (CL) intolerant. They are mainly designed to improve visual acuity in irregular corneas, and secondarily, they help to provide healing and comfort in ocular surface disorders. BostonSight SCLERAL (BSS) lenses have been dispensed for this case. Herein, a few strategies are used to achieve optimal fit, considering the visual acuity improvement and comfort with lenses.


  Case Reports Top


Case 1

A 10-year-old male presented to the clinic with blurring of vision for distance in both eyes. His best corrected visual acuity (BCVA) in both eyes was 20/200 with a refractive error of − 10.00 D spherical equivalent ratio (SER) in both eyes. A scan showed axial length of 25.10 mm in the right eye and 25.55 mm in the left eye, and 4.66 mm anterior chamber depth in the right eye and 4.50 mm in the left eye. Corneal topography [Figure 1] was performed for both eyes, and the Sim K was 61.8 D @ 100; 51.6 D @ 10 in the right eye and 62.9 D @ 70; 47.2 D @ 160 in the left eye. Ultrasonic pachymetry showed diffuse corneal thinning across the cornea. The patient was diagnosed as keratoglobus in both eyes and was recommended corneal gas permeable (GP) lenses for visual rehabilitation. Trial with corneal GP aspheric design lenses was performed with the patient's consent. RGP lenses were tried, and the lenses were having compromised fit and unstable in all gazes. Scleral lens trial [upper half of [Figure 2]] was performed on both eyes. Based on the clinical experience, we started the trial with higher sagittal depths in the BSS diagnostic trial sets. BCVA with BSS lens was 20/60 in both eyes, and pinhole improved to 20/30. Higher eccentricity was added on the lenses to further improve the visual acuity to 20/30 in both eyes. As the patient reported difficulty in removing lenses after 4 h of lens use, smart channels were added to soften further the landing of the haptic surface on the conjunctiva[4] and to prevent a seal-off effect. The patient wore the lens for 1 week; he reported that the previous symptoms of pressure and difficulty with lens removal had improved. Both eyes showed optimal fit with no mid-haptic compression [upper half images of [Figure 2]].
Figure 1: Corneal topography of the right and left eyes of case 1

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Figure 2: Slit-lamp images of the right and left eyes with scleral lenses of case 1 (upper half of image) showing no mid-haptic compression after adding smart channels and of case 2 (lower half of image) showing significant mid-haptic compression in both eyes and conjunctival prolapse in the left eye

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Case 2

A 30-year-old male presented to the clinic with blurring of vision for distance in both eyes. His BCVA was 20/400 in the right eye and 20/200 in the left eye, with a refractive error of − 8.00 D SER in the right eye and − 7.00 D SER in the left eye. Anterior chamber depth was 4.77 mm in the right eye and 4.58 mm in the left eye. Corneal topography [Figure 3] was performed for both eyes, and the Sim K was 70.9 D @ 130; 58.0 D @ 40 in the right eye and 74.5 D @ 100; 53.8 D @ 170 in the left eye. Ultrasonic pachymetry showed diffuse corneal thinning across the cornea. The patient was diagnosed as keratoglobus in both eyes and was recommended corneal GP lenses for visual rehabilitation. Trial with corneal GP aspheric design lenses was performed with the patient's consent. RGP lenses were fitted in the initial visits, and in the follow-up visit, the lens tended to pop out from the eyes. Scleral lenses were prescribed, and the patient has been constantly using them for more than 5 years. Visual acuity improved to 20/30 in both eyes. On slit-lamp examination, mid-haptic compression was noted in both eyes [[Figure 2] lower half images] and conjunctival prolapse was noted in the left eye [[Figure 2] lower half right-side image], and suction pressure was noted while removing the lenses. After 3 years of lens use, the patient presented to the clinic with sudden onset of decrease in vision and pain in the right eye. On slit-lamp examination, corneal edema was noted and diagnosed as corneal hydrops. Six months after resolution of corneal hydrops on administering intracameral C3F8 injection and with corneal compressive sutures, the patient started using the scleral lenses in the right eye and his vision improved to 20/60 in the right eye. In the next few months, the patient developed corneal hydrops in the left eye too. Though the corneal curvature remains the same over the period, the potential reason for hydrops could be the suction pressure created under the lens.
Figure 3: Corneal topography of the right and left eyes of case 2

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Case 3

A 25-year-old male presented to the clinic with blurring of vision for distance in the right eye and no vision in the left eye for 5 years. His BCVA was 20/600 in the right eye and hand movement in the left eye. Anterior chamber depth was 5.43 mm in the right eye and it could not be measured in the left eye because of failed graft with corneal scarring. Corneal topography [[Figure 4 left] side] was performed for the right eye, and the Sim K was 60.8 D @ 85; 52.7 D @ 175 in the right eye. Ultrasonic pachymetry showed diffuse corneal thinning across the cornea. The patient was diagnosed as keratoglobus in the right eye and failed graft in the left eye and was recommended corneal GP lenses for visual rehabilitation. Scleral lens [[Figure 4] right side] was tried on the right eye, considering advanced keratoglobus where the RGP lens may not be stable. Visual acuity improved to 20/60 in the right eye. On slit-lamp examination, mid-haptic compression was noted in the right eye [[Figure 4] right side], and suction pressure was noted while removing the lenses. This patient had already developed hydrops and descemet's membrane (DM) tear and healed after he was administered intracameral C3F8 injection together with corneal compressive sutures. This patient continued to wear scleral lenses in the right eye for visual rehabilitation and is not keen to go for surgical option as he is one eye dependent.
Figure 4: Corneal topography (left side) and anterior segment photography (right side) of the right eye of case 3

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In all three cases, the scleral lens was acceptable with an adequate corneal clearance (no touch) and with no air bubble in the fluid after 4 h of lens use. But the first case did not show mid-haptic compression after adding smart channels. Case 2 and case 3 showed mid-haptic compression after 4 h of lens use and the patients subjectively noticed difficulty in removing the lenses. Corneal clearance of 200–300 μm was noted in all cases after 4 h of lens use, which was adequate as per the manufacturing guideline.[5] Two Patients reported sensation of pressure while wearing the device either subjectively or objectively. In two out of three cases, hydrops developed after scleral lens wear and suction pressure was noted while removing the lenses. On slit-lamp examination, conjunctival prolapse and mid-haptic compression were noted while assessing the fit. The relationship between the suction pressure and conjunctival prolapse has been discussed already. This could be the possible reason for the development of corneal hydrops in these two patients.


  Discussion Top


Scleral contact lenses are lenses that rest on sclera and do not touch the cornea, with a space present between the scleral lens and the cornea. This is termed as corneal clearance of scleral lenses and is due to vaulting of lens. The lens is filled with fluid before insertion in the eye. The fluid can be unpreserved saline or normal saline (0.9% sodium chloride).[6],[7]

BostonSight scleral contact lenses allow the corneal clearance independently of the base curve and internal optical zone using spline technology. An acceptable fit is characterized by adequate corneal clearance with no lens impingement, no lens movement, and no compression of blood vessels. If the fit is acceptable, the lens can be left in the eye, so that the patient experiences both comfort and improved vision during trial. Front surface eccentricity (FSE) can be added to improve the visual acuity if there is reduced visual acuity with spherical front surface lens, especially in highly irregular cornea.

In ectatic cornea, the presence of higher-order aberrations reduces visual acuity; this can be improved further by adding FSE or toricity, or wave front aberration correction to spherical scleral lens improves the visual acuity.[8] A previous report attributed the occurrence of corneal hydrops to the suction generated during lens removal.[9] Radial channels are another unique design in BostonSight scleral contact lenses, which integrate a series of radial venting channels between the haptic and the sclera that function as a safety valve through which tears get aspirated alone, without air bubbles, and without the development of suction. Radial channels were added in the cases to facilitate ease removal of the lenses.[10] Out of three cases, in the first case, the radial channels were added to the lenses and it facilitated lens removal. In rest two cases, lenses were dispensed with mid haptic compression and in follow-up visit corneal hydrops were noted in both cases (case 2 and case 3). This case series describes two important aspects, which are improvement in visual acuity and comfort of the lenses.[10] These two aspects are important for contact lens practice to reduce contact lens dropouts.


  Conclusion Top


Our case series emphasizes the different fitting strategies of scleral lenses in keratoglobus, considering improvement in visual acuity as well as comfort of lens use. Different strategies of fitting scleral lenses in keratoglobus are to i) consider changing the FSE if there is pinhole improvement with spherical front surface lens and ii) consider adding channels, especially in case of keratoglobus when there is suction while removing the lenses, as this pressure can induce corneal hydrops for extended scleral lens user.

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.

Acknowledgement

No authors have any proprietary interests in the contents included in this article. The contents of this article have not been presented in any national or international meeting.

Financial support and sponsorship

Hyderabad Eye Institute and Hyderabad Eye Research Foundation.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Sridhar M, Mahesh S, Bansal A, Rao GN. Superior pellucid marginal corneal degeneration. Ophthalmology 2004;18:393-9.  Back to cited text no. 1
    
2.
Raizada K, Sridhar MS. Nomogram for spherical RGP contact lens fitting in patients with pellucid marginal corneal degeneration (PMCD). Eye Contact Lens 2003;29:168-72.  Back to cited text no. 2
    
3.
Edrington TB, Barr JT, Zadnik K, Davis LJ, Gundel RE, Libassi DP, et al. Standardized rigid contact lens fitting protocol for keratoconus. Optom Vis Sci 1996;73:369-75.  Back to cited text no. 3
    
4.
Carrasquillo K, Byrnes, S. Corneal edema and scleral lenses. Cont Lens Spect 2018;33:34-41.  Back to cited text no. 4
    
5.
6.
Rathi VM, Mandathara PS, Dumpati S, Vaddavalli PK, Sangwan VSJIjoo. Boston ocular surface prosthesis: An Indian experience. Indian J Ophthalmol 2011;59:279-81.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Jacobs DS. Update on scleral lenses. Curr Opin Ophthalmol 2008;19:298-301.  Back to cited text no. 7
    
8.
Hussoin T, Le H-G, Carrasquillo KG, Johns L, Rosenthal P, Jacobs DS, et al. The effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device. Eye Contact Lens 2012;38:300-5.  Back to cited text no. 8
    
9.
Rathi VM, Mandathara PS, Vaddavalli PK, Dumpati S, Chakrabarti T, Sangwan VS. Fluid-filled scleral contact lenses in vernal keratoconjunctivitis. Eye Contact Lens 2012;38:203-6.  Back to cited text no. 9
    
10.
Rathi VM, Mandathara PS, Taneja M, Dumpati S, Sangwan VS. Scleral lens for keratoconus: Technology update. Clin Ophthalmol 2015;9:2013-8.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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