OPTOMETRY CASE REPORT. Circinate corneal scarring

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1 OPTOMETRY CASE REPORT Circinate corneal scarring Clin Exp Optom 2004; 87: 1: Sandra Codson* BOptom PgDipAdvClinOpt Adrian Bruce+ BScOptom PhD * Victorian College of Optometry, The University of Melbourne + Clinical Vision Research Australia, Victorian College of Optometry A 56year-old man presented with symptoms of monocular diplopia and reduced vision in his left eye. Visual acuities were R6/6, L6/12. At his previous visit left visual acuity was 6/6. An irregular area of anterior corneal stromal scarring was evident, encroaching on the visual axis of the left eye. Rigid lens fitting improved left visual acuity to 6/6, however, lens wear caused a corneal abrasion over the lesion after one to two hours of wear. Several other contact lens and surgical strategies were employed to successfully address the visual requirements of the patient. Received: 31 July 2002 Revised: 6 June 2003 Accepted for publication: 17 June 2003 Key words: circinate corneal scarring, phototherapeutic keratectomy, RGP lenses There is a range of corneal conditions that lead to scarring or opacities. These include dystrophies, degenerations, trauma and infections, all of which can affect vision or contrast sensitivity, if corneal surface distortion develops. A corneal scar may also affect vision directly due to light scatter from the opacity. The visual aspects of corneal surface distortion may be corrected with rigid gas permeable (RGP) contact lenses. Where the surface is particularly irregular, reverse geometry lenses can be fitted, as in post-graft correction. This case concerns the development of a corneal scar, and the contact lenses and other treatments used to improve the quality of vision. It involves a number of rigid gas permeable fitting strategies and methods for estimation of the elevation of a corneal scar. CASE REPORT A 56-year-old man attended the Melbourne Optometry Clinic of the Victorian College of Optometry in 1996 for routine ocular assessment. He reported a history of Bell s palsy, chronic fatigue and hypertension. At that time, visual acuities were 6/6 right and left. Slitlamp examination was unremarkable, with no corneal lesion recorded. At routine optometric review in January 1998, a left corneal scar was first noted, although the patient s vision remained unaffected. Having noted ghosting and image doubling, which were worse at night, and a gradual onset of reduced vision in the left eye, the patient returned for optometric assessment in January The visual acuities at this appointment were R6/6, L 6/12 with R+2.00/-1.00~100, Lt1.00/ -1.00~90. Monocular diplopia was evident in the left eye even with spectacle correction. Refraction in the left eye was recorded as variable, there was no improvement in visual acuity with pinhole and an irregular corneal reflex was recorded. Slitlamp examination revealed an irregular area of anterior corneal stromal scarring superior to and encroaching on the visual axis in the left eye (Figure la). It measured approximately three millimetres in diameter. The lesion was raised, as evidenced by the negative staining at its margin (Figure lb). As the lesion appeared to have progressed during a two-year period, the patient was referred for ophthalmological assessment. Ophthalmological opinion suggested that the corneal condition was static, with 28

2 Circinate corneal scarring Coulson and Bruce Figure lb. The region overlying the corneal scar exhibitsnegative staining with sodium fluorescein (8x magnification with blue light and wrattan Fiter) Figure la. A left circinate corneal scar impinging on the visual axis (with fenestrated RGP) in primary gaze as it appeared in January 2000 (12x, white light) no treatment indicated. It was described as a focal ring-like area of scarring associ- ated with slight corneal thinning. There was speculation on a possible aetiology of herpes simplex virus, although no specific signs were present. The patient was returned to optometric care for contact lens fitting. Contact lens correction Figure lc. Medmont axial topography shows steepening in the region of the scar but poor reproducibility 29 To improve the reduced visual acuity in the left eye, the patient was fitted with contact lenses in March He planned to wear reading glasses over his contact lens correction. Keratometrywas R8.00 at90,8.10at 180 and L 7.80 at 90,8.00 at 180,with distorted mires apparent in the left eye. Corneal topography using the Topographic Modelling System (TMS2, Tomey, New York) showed a normal image for the right cornea but a disrupted image of the left with localised areas of drop-out and little useful information produced about the lesion. Instantaneous plots gave only disjointed maps. Medmont E300 videokeratoscopy (Figure l c ) was available to us in December 2000 and it modelled an area of corneal steepening that corresponded approximately to the fluorescein imaging of the scar. Humphrey Atlas topography

3 Circinate corneal scarring Coulson and Bruce Figure 2a. Initial RGP lens with spherical 7.9 BOZR rests heavily on the cornea in the region of the scar (12x magnification with blue light and wattan filter) Figure 2b. Corneal abrasion evident following RGP wear also used in December 2000, estimated the elevation of the scar to be 50 to 100 microns, however, the results from the Medmont and Humphrey were not available to us at the time of the initial fitting in March The initial contact lenses ordered were of tricurve design, with parameters of R 8.0/10.0/+1.00, L 7.9/10.0/t1.25, BOZD was 8.0 and peripheral curves +0.8 (0.6), (0.4) in a Boston EO material (Australian Contact Lenses, Melbourne, Australia). The fluorescein pattern showed an alignment fitting in the right eye and some touch in the scarred region in the left eye (Figure 2a). Visual acuities of R and L 6/6 were achieved with the contact lenses and the patient noted significant subjective improvement with the reduction of ghosting and monocular diplopia. At an after-care visit two weeks following delivery of the lenses, the patient reported that overall comfort was improving, as he was able to wear the lenses seven days per week for a maximum of eight hours. There was no corneal staining evident following two hours ofwear. The patient had been using lubricating drops. At an after-care visit in May 2000, the patient reported that the left eye was some- times uncomfortable with foreign body sensation and epiphoria during wear. While very satisfied with the level of vision and lack of ghosting when wearing the contact lenses, the patient was unable to wear the lenses longer than eight hours per day. Mild corneal sodium fluorescein staining over the region of the scar was first noted at this visit. On examination of the fitting of the RGP lenses, the left lens appeared to be bearing on the scarred region. The patient was asked to cease wear, report any worsening of symptoms and return for review in one week. At review, the staining had resolved and, as a trial, the patient was asked to wear the right lens alone. The left lens was reordered with a steeper BOZR of 7.80 mm to attempt to bridge the irregular corneal surface, leaving only a very light touch. On delivery of the steeper RGP lens, the patient reported that wearing the right lens only (wearing time eight to 12 hours per day) was preferable to spectacle wear but he experienced a slight sensation of left blur and was motivated to correct this. Unfortunately, while resolving the monocular diplopia, the 7.80 BOZR RGP lens could be tolerated for only about one half of an hour to two hours before removal was required. There was appropri- ate centration, alignment and edge clearance displayed on examination of the contact lenses. Rubbing of the elevated scar in the left eye through a region of corneal touch appeared to cause deep corneal abrasion after approximately one hour of wear (Figure 2b). In an attempt to vault the elevated scar and prevent abrasion, a reverse geometry lens (RGL) design was adopted. The choice of parameters for the left lens was BOZR 8.0, total diameter 10.6, t1.75 D with BOZD 7.0 and peripheral curves -0.8(0.9), +1.5/(0.45), +2.50(0.45) in a Boston XO material. With trial fitting this lens gave apical clearance, lightly touching the lesion, and a large accompanying bubble. Unfortunately, on delivery of the lens there appeared to be more significant touching and at review the new lens design had not relieved the patient s symptoms. The contact lens company kindly provided three further designs for trial wear. These were: 1. Asteep quadcurve design (BOZR 7.70/ G.O/plano, 8.00/9.3, 9.5/9.9, 11.0, 10.5), which again produced a fitting pattern of touch on the scar with an inferior air bubble. 2. A channel design (parameters 7.90/ 10.6/+1.25, channel of 7.80 BOZD

4 Circinate corneal scarring Coukon and Bruce Tear layer profile for reverse geometry lens BOZR = 8.05 mm, diameter = 10.5, second curve = 7.25 mm ln X o Chord radius from lens centre (mm) Figure 3a. Tear layer profile Figure 3b. RGL (8.05 BOZR) fluorescein pattern Figure 3c. Dimple veiling in fenestrated RGL following wear to 6.5 diameter, +1.5 (0.4), +2.5[0.4]), which produced a small inferior air bubble and a wide region of superior contact. 3. A reverse geometry lens was ordered with 8.2 BOZR in an attempt to better clear the mid-peripheral lesion. The parameters were 8.2/10.6/+2.75, peripheralcurves-0.8 (0.9), +1.5 (0.45), +2.5(0.45). This lens still exhibited mild contact on the scar area. None of the above fittings improved the patient s wearing time when a home trial of each was undertaken. At an after-care visit in September 2000, the patient again reported minimal wearing time in the left eye, which was consistently sore with lens removal and remained painful for a period following lens removal, correlating to the wearing time that day. Fluorescein staining was evident in the region of the scar with slitlamp biomicroscopy following lens removal, indicating epithelial abrasion. Tear layer profiling was undertaken to determine the best clearance of the lesion (Figure 3a). This estimated the corneal elevation at this point to be around 90 pm with a corneal Ro of 8.0 and eccentricity value of 0.4. This method suggested that the 8.05 BOZR lens would be the most ap propnate lens to vault or provide minimal touch in the mid-peripheral zone and this was ordered in November 2002 with parameters: 8.05/10.6/+2.00, BOZD 7.0, peripheral curves of -0.8 (0.9), +1.5(0.45), +2.5(0.45) of Boston EO material (ACL). It is of interest that the elevation approximated by the Humphrey topographer was in the range of 50 to 100 pm. In mid-december, wearing time for the left lens had increased to four to eight hours. On slitlamp examination, it appeared that the increased comfort was due to the lens binding to the cornea, with a uniform fluorescein pattern beneath the lens. Fenestrations were introduced in the lens to counteract this suction effect. Unfortunately, after only 10 minutes of wearing the fenestrated lens, dimple veiling occurred with associated reduced acuity (Figure 3c). Following the exploration of several contact lens fitting options without achieving the desired wearing time and with the patient still 31

5 ~ ~~ Circinate corneal scarring Coulson and Bruce Figure 4a. Corneal lesion post-operatively, residual opacity still apparent Figure 4b. Fluorescein pattern shows circular region of laser treatment. The area of negative staining is reduced indicating reduced corneal elevation. highly motivated to improve the vision in his left eye, further ophthalmological assessment was sought. Laser treatment Ophthalmological assessment in April 2001 suggested surgical treatment to reduce the scar elevation. The technique was focal ablation of the affected area of the corneal surface with phototherapeutic keratectomy (PTK). The aim was to reduce the scar elevation and produce a regular corneal bed following the procedure. The method utilised a three-millimetre ablation zone 70 pm deep. Following surgery, uncorrected vision in the left eye improved from 6/24 to 6/9. Pleased with the outcome, the patient noted some residual ghosting. Although some corneal opacity remained with white light examination (Figure 4a), fluorescein pooling indicated reduced corneal elevation in the area of the scar (Figure 4b). The patient required two further manual scrapings of the area with a scalpel to smooth residual peaks of the scar. An improved RGP fluorescein fitting pattern was achieved (Figure 4c) with a tricurve lens of parameters 7.9/10.0/0.75, BOZD 8.0 and peripheral curves of +0.8(0.6), +1.5(0.4) in a Boston XO material. Since then, RGP wear has been successful with a left visual acuity of 6/6. DISCUSSION Figure 4c. Post-operative RGP fit shows pooling rather than bearing (as in Figure 2a) in the region of the scar Contact lenses are one solution to combat the visual disturbance caused by corneal irregularity. An RGP contact lens is superior to spectacle or soft contact lens correction because it creates a tear lens between the cornea and the contact lens that will neutralise the surface irregularity to improve optical clarity. RGP contact lenses are preferentially used in keratoconic contact lens fitting to correct cor- neal ectasias, post-lasik and post-surgery, to correct for asymmetric corneal grafts..2 In this case, the corneal aberration was due to an elevated corneal scar but similar fitting principles can be employed. This patient displayed typical symptoms of visual disruption associated with corneal irregularity, including monocular diplopia and ghosting of images, when uncorrected or with spectacle correction. Glare sensitivity is another common visual disturbance shared by such patients. 32

6 I Circinate corneal scarring Coulson and Bruce The aetiology of the elevated corneal scar was not clear but ophthalmological assessment suggested stromal herpes simplex viral keratitis as a possible cause. Other possible causes include corneal dystrophy or Salzmann s nodular degeneration (both typically bilateral), phlyctenulosis (generally associated with pain and corneal neovascularisation) and trauma (although there was no history to support this). Elevated corneal nodules have been described as an inhibition to contact lens fitting in other conditions such as keratowhere contact lens intolerance can lead to the need for penetrating keratoplasty. The mid-peripheral location of the scar described in this case caused it to be particularly challenging to fit. Where an apical corneal scar may be more easily vaulted with a steep contact lens and has a somewhat regular bearing region, the small decentred area of elevation proved more vulnerable to contact pressure. Contact lens intolerance was evidenced by reduced wearing time, increased glare sensitivity, excessive epiphora and pain associated with corneal abrasion. Optometrists employ various instruments to assist with contact lens fitting. Estimation of corneal curvature with a keratometer relies on data gathered from the central corneal region. Although disruption of keratometry mires provided an indication of corneal surface quality, further information regarding the quality and elevation of the peripheral cornea was required. Videokeratoscopy systems for mapping corneal topography are invaluable in assessment of regular corneas, however instrument limitations such as poor repeatability, misalignment and reduced accuracy in the corneal ~eriphery~,~ can minimise their usefulness. Ideally, assessment of corneal topography at the initial fitting visit would allow clear visualisation of the scar and an estimate of its maximum elevation. The Medmont E300 instrument appeared to offer the best visualisation of the lesion, whereas the Humphrey Atlas suggested an elevation that coincided most closely with the tear layer profile and fluorescein fitting patterns. The tear layer profile suggested that the scar elevation of 90 pm was greater than the capacity of the steepest rigid lens to vault the cornea without causing dimple veiling. A reverse geometry lens was one option used to attempt to clear the scar. The reverse geometry RGP lens design is commonly used in graft fitting2 to give maximum corneal clearance and prevent graft complications. It differs from a traditional tricurve or aspheric RGP design in that the second curve is steeper rather than flatter than the first, increasing the clearance of the lens from the cornea. Limiting factors in the creation of large central corneal clearance with a steep RGL are reduced acuity with the occurrence of dimple veiling and difficulty with lens removal. Lid interaction in this case created a suction effect that was addressed unsuccessfully with lens fenestration. Another option that could have been considered was a piggyback system or bandage soft contact lens. This strategy was not implemented due to the complication of lens handling routines. With the exhaustion of contact lens fitting options, surgical intervention was prompted by the patient s high motivation to have contact lens correction in the left eye, despite normal vision in the right. Phototherapeutic keratectomy is a method of surgically reshaping and smoothing the corneal surface.6 Wards describes four cases of subjects with keratoconus in whom PTK was performed. Each had become intolerant to contact lens wear following the development of raised nodular superficial scars. Ablation with a 193 nm excimer laser allowed smoothing of the corneal surface and resumption of RGP contact lens wear. PTK has also been used in the reduction of central corneal islands following photorefractive keratectomy, to restore normal topography. This case shows that there are many fitting strategies the optometrist can employ to achieve the improved image quality offered by contact lens correction compared to spectacle correction for patients with an irregular corneal surface. Other options such as excimer laser surgery can be considered. ACKNOWLEDGEMENT We wish to thank Australian Contact Lenses (Melbourne) for assistance with contact lens design. REFERENCES 1. Woodward EG. Post-keratoplasty. In: Phillips AJ, Speedwell L, eds. Contact Lenses, 4th ed. London: Butterworth- Heinmann, 1997: Lindsay RG. Case report: Post-keratoplasty contact lens management. Clin Exp Optom 1995; 78: Ward MA, Artunduaga G, Thompson KP, Wilson LA, Stulting RD. Phototherapeutic keratectomy for the treatment of nodular subepithelial corneal scars in patients with keratoconus who are contact lens intolerant. CLAOJ1995; 21: Mandell RB. A guide to videokeratography. ICLC 1996; 23: Keller PR, van Saarloos PP. Perspectives on corneal topography: a review of videokeratoscopy. Clin Exp Optom 1997; 80: Rachid MD, Yo0 SH, Azar DT. Phototherapeutic keratectomy for decentration and central islands after photorefractive keratectomy. Ophthalmology 2001; 108: Fasano AP, Moreira H, McDonnell PJ, Sinbawy A. Excirner laser smoothing of a reproducible model of anterior corneal surface irregularity. Ophthalmology 1991; 98: Author s address: Sandra Coulson Victorian College of Optometry 374 Cardigan Street Carlton VIC 3053 AUSTRALIA 33