cxo_658 229..232

CLINICAL COMMUNICATION

Bitoric rigid gas permeable contact lens fitting forthe management of a corneal scar caused by herpes

zoster ophthalmicus

Clin Exp Optom 2012; 95: 229–232 DOI:10.1111/j.1444-0938.2011.00658.x

Victoria de Juan* MScRaúl Martín*† PhDGuadalupe Rodríguez*† MSc* IOBA-Eye Institute, University ofValladolid, Valladolid, Spain† Department of Physics TAO, School ofOptometry, University of Valladolid,Valladolid, SpainE-mail: victoria@ioba.med.uva.es

Empirical fitting of a bitoric rigid gas permeable contact lens for the management of ascarred irregular cornea caused by herpes zoster ophthalmicus is described. Two cornealscars, which affect the pupil axis, caused an irregular cornea and produced low visualacuity and anisometropia. Two contact lenses were necessary to complete the fitting.Visual acuity improved from 0.2 to 1.0. The rigid gas permeable lenses can be a goodalternative in the management of patients with irregular corneas caused by herpes zosterophthalmicus.

Submitted: 22 March 2011Revised: 25 May 2011Accepted for publication: 7 June 2011

Key words: astigmatism, contact lenses, cornea, herpes zoster ophthalmicus

Corneal scarring following herpes zosterophthalmicus (HZO) can frequently causea significant reduction of vision due tocorneal leukomas and irregular astigma-tism.1 Small peripheral scars might notaffect visual quality, but large mid-peripheral scars can cause severe astigma-tism. Many of these patients requirephotorefractive keratectomy,1 keratopros-thesis2 or keratoplasty1 for recovery ofvisual acuity. Rigid gas-permeable (RGP)contact lenses can mask significantamounts of irregular astigmatism and canimprove visual acuity in some of thesepatients.3,4

This paper presents a case in whichbitoric RGP contact lenses were pre-

scribed to improve the vision of a patientwith corneal leukomas and irregularastigmatism secondary to herpes zosterkeratitis.

CASE REPORT

A 62-year-old male patient was referred fora contact lens fitting. The patient had beendiagnosed with herpes zoster ophthalm-icus five years earlier. Painful cutaneouslesions appeared on the right side of hisface and these were associated with blur-ring and severe ocular pain in the right eye.The patient did not wear glasses or contactlenses. His ocular history revealed no othernotable findings. He did not have a signifi-

cant familial ocular history. His generalhealth was excellent and he was not takingany medication on a regular basis.

The uncorrected visual acuities were 0.2in the right eye and 1.2 in the left eye.Visual acuity in the right eye was 0.6 with asubjective refraction of plano/-4.00 ¥175°. Slitlamp examination of the righteye showed two corneal scars in the mid-periphery, involving the pupil axis, at oneand six o’clock, respectively (Figure 1A).The left eye was normal.

Modifications of the corneal curvatureand pachymetry were caused by thesescars along the vertical axis (Figures 2Aand 2B), producing corneal astigmatism(Figures 2C and 2D).

C L I N I C A L A N D E X P E R I M E N T A L

OPTOMETRY

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Orbscan II (Bausch & Lomb, Inc, Roch-ester, NY, USA) revealed an irregularcornea with astigmatism of 13.8 D. TheOrbscan-simulated keratometric readingswere 43.6 D (7.74 mm) @ 170° ¥ 57.8 D(5.84 mm) @ 80°. Manual keratometry(Ophthalmometer OM-1, Topcon, Japan)

was 40.91 D (8.25 mm) @ 180° ¥ 44.41 D(7.60 mm) @ 90°.

Keratographic topography (OculusOptikgeräte GmbH, Wetzlar, Germany)showed high astigmatism of 10 D. Thekeratograph-simulated keratometry read-ings were 44.00 D (7.67 mm) @ 160° ¥

54.00 D (6.25 mm) @ 70°. The ring seg-ments of the topographical image weredistorted (Figure 1B).

A bitoric RGP contact lens was proposedto improve visual acuity in the right eye. Anempirical fitting was provided. After thetrial fitting of two diagnostic contact lensesin the same visit (Table 1, Figure 3), thedefinitive contact lens was calculated witha back optic zone radius of 7.70/7.35 mm,total diameter 9.60 mm, power +1.50 Dand Boston ES (BIAS-MAC lens design ofHecht Contactlinsen/Conoptica, Barce-lona, Spain). The examination revealedgood centration, movement and tearexchange. The fluorescein pattern(Figure 1C) showed good central align-ment with two paracentral clearances inthe two scar zones (vertical meridian),mild peripheral alignment with optimalclearance under the peripheral curve andgood edge clearance to facilitate tearexchange. This fluorescein pattern wasconsistent with the Orbscan anteriorsurface elevation map (Figure 1D).

At the three-month after-care visit, thepatient indicated that he was wearing thelens approximately eight hours per day,six to seven days per week without discom-fort. No visual acuity changes were found.Slitlamp examination did not revealcorneal or conjunctival staining or anyother ocular complications associated withcontact lens wear.

DISCUSSION

Contact lens fitting might be requiredafter herpes zoster ophthalmicus foroptical reasons, such as the correction of

Trial lens BOZR(mm)

Diameter (mm) Power (D) Geometry/Model Over refraction VA Comment

1 7.70 9.60 -3.00 Aspheric/BIAS S +4.50 0.8 Visual fluctuation2 7.70/7.35 9.60 -3.00 Bitoric/BIAS MAC +4.50 1.0 Good alignment

Material for all diagnostic lenses: Boston ES, Hecht Contactlinsen/Conoptica, Barcelona, Spain.BOZR: back optic zone radius; VA: visual acuity with over correction in trail frame

Table 1. Trial contact lens parameters used to calculate the definitive contact lens

Figure 1. A. Slitlamp examination showed two corneal scars along the vertical axis. Oneof the scars affects the pupil axis. B. Ring segments of the topographical image of thedescribed case. C. The fluorescein pattern with the toric rigid gas-permeable lens showsthe central alignment and two apical clearances in the scar zone. D. Orbscan elevationtopography shows an irregular corneal surface with high astigmatism (anterior elevationas the best fitting surface).

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irregular astigmatism, high regular astig-matism, anisometropia and secondaryaniseikonia, as well as ametropia, and incases where the patient wants to wearcontact lenses in preference to spectacles.In the present case, the contact lenseswere fitted to improve visual acuity andmaintain some degree of binocular func-tion. Additionally, the lenses permittedthe resumption of some leisure activities,such as shooting and hunting.

The RGP contact lenses essentiallycreate a new spherical refraction surface,which allows the tear film beneath thecontact lens to neutralise the corneal astig-matism. In many cases, an irregularcornea can be fitted with spherical oraspheric RGP designs. Although sphericaldesigns often fail due to poor fitting,specialty lens designs might provide astable, comfortable lens that offers visualimprovement.5 Back surface toric andbitoric designs are most useful when thecorneal topography consists of largeamounts of astigmatism. A spherical backsurface has difficulty centring on the eyeand the sloping corneal surface causesexcessive movement and edge lift in thevertical meridian. This excessive move-ment results in discomfort and visual fluc-tuations (Table 1). For this reason, abitoric contact lens was fitted to lessen theedge lift in the vertical meridian anddecrease movement. In this type of lens,the anterior surface has two different radiito compensate for the residual astigma-tism. This residual astigmatism is createdby the lack of parallelism between thecorneal astigmatism and the back surfaceof the contact lens. It may also be causedby the difference between the refractiveindex of the lens material and the tears.The final refractive effect is spherical andthis is called a compensated bitoric lens.The back toric surface corrects the refrac-tive cylinder created by the corneal toricityand the front surface incorporates the cor-rection for the induced astigmatism.6 Thelens is called BIAS MAC and will alwayshave two back meridians with a constantdifference of 0.35 mm. The practitionerchooses the flattest back radius of thecontact lens according to the flattestmeridian of the cornea and the other back

Figure 2. A. Detail of the upper scar. B. Alteration of the corneal surface as shown byoptical section. C. Orbscan keratometric map shows high astigmatism with a regularpattern. D. Keratographic keratometric map gives good agreement with the Orbscankeratometric map.

Figure 3. A. The fluorescein pattern with the first trial lens. The sloping corneal surfacecauses excessive movement and edge lift in the vertical meridian. B. The fluoresceinpattern with the second trial lens shows good alignment.

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radius is selected by the manufacturer(0.35 mm steeper).

In irregular corneas, traditional fittingnomograms might not be appropriate.Therefore, computerised corneal topogra-phy has been invaluable in assisting thepractitioner to select the most appropriateRGP lens design. The quality of the cap-tured image is a crucial factor for accuratetopographic results.7

In this case, empirical fitting was pro-posed, aiming for the proper fluoresceinimage with a contact lens and cornealalignment.3 This type of fitting mightbe challenging and time consuming,although specialty lens designs (forexample, toric and reverse-geometry)could take less fitting time than standardor aspheric RGP lenses due to bettercentration and stabilisation.8 For thesereasons, these contact lenses have beenproposed after corneal graft surgery9 orfollowing laser refractive surgery.8 In thepatient in the present study, a bitoriccompensated RGP contact lens was fittedafter only two diagnostic lenses and weobtained good centration with no supe-rior dislocation (Figure 1C).

Visual acuity with RGP contact lenswas significantly improved (from 0.2 to1.0) because the tear film underneaththe contact lens neutralises the cornealsurface irregularities, similar to previousreports.4 The visual acuity with the contactlens (1.0 in the right eye) was similar tothe previous visual acuity (subject notwearing glasses before herpes zoster oph-thalmicus). Visual acuity could be similarin both eyes (left eye visual acuity was 1.2).

Acceptance of the contact lens was highwith approximately eight hours per dayof wear; however, some authors concludethat the long-term success for these pa-tients wearing contact lenses is poor.10 Analternative to contact lens fitting foroptimal visual gain is eye surgery with dif-ferent techniques (for example, kerato-plasty, topographic-linked corneal excimerlaser ablation and wave-front guidedaberration-controlled laser-assisted in situkeratomileusis). Eye surgery is difficult andof limited use in cases of very high astigma-tism and insufficient corneal thickness,and limited by the availability of donor

tissue, the difficulty of the techniqueand post-operative complications. Contactlenses are the first choice and sometimesthe best solution for optical rehabilitationin eyes with irregular corneal surfaces.3

CONCLUSION

The fitting of contact lenses in a patientwho has corneal scars caused by herpeszoster ophthalmicus is generally difficult.Toric geometry contact lens fitting can bea good alternative in these cases. Analysisof fluorescein patterns could be usefulwhen fitting RGP contact lenses and couldtake less time and fewer visits than stan-dard or aspheric RGP contact lenses inthese patients.

REFERENCES

1. Kaufman SC. Use of photorefractive keratectomyin a patient with a corneal scar secondary toherpes zoster ophthalmicus. Ophthalmology 2008;115 (Suppl): S33–S34.

2. Todani A, Gupta P, Colby K. Type I Boston kerato-prosthesis with cataract extraction and intraocularlens placement for visual rehabilitation of herpeszoster ophthalmicus: the ‘KPro Triple’. Br J Oph-thalmol 2009; 93: 119.

3. Titiyal JS, Sinha R, Sharma N, Sreenivas V, Vaj-payee RB. Contact lens rehabilitation followingrepaired corneal perforations. BMC Ophthalmology2006; 6: 11.

4. Jupiter DG, Katz HR. Management of irregularastigmatism with rigid gas permeable contactlenses. CLAO 2000; 26: 14–17.

5. Watanabe RK. Clinical Cases in Contact Lenses.Woburn, MA: Buttterworth-Heinemann, 2002.

6. Efron N. Contact Lens Practice. Oxford, UK:Buttterworth-Heinemann, 2002.

7. Chui W, Cho P. A comparative study of the perfor-mance of different corneal topographers on chil-dren with respect to orthokeratology practice.Optom Vis Sci 2005; 82: 420–427.

8. Martin R, Rodriguez G. Reverse geometry contactlens fitting after corneal refractive surgery compli-cations. J Refract Surg 2005; 21: 753–756.

9. Szczotka RB, Lindsay RG. Contact lens fitting fol-lowing corneal graft surgery. Clin Exp Optom 2003;86: 244–249.

10. McMahon TT, Devulapally J, Rosheim KM, Putz JL,Moore M, White S. Contact lens use after cornealtrauma. J Am Optom Assoc 1997; 68: 215–224.

Corresponding author:Mrs Victoria de JuanIOBA Eye InstituteUniversity of ValladolidPaseo de Belén, 1747011, ValladolidSPAINE-mail: victoria@ioba.med.uva.es

Bitoric contact lens fitting after herpes zoster ophthalmicus de Juan, Martín and Rodríguez

Clinical and Experimental Optometry 95.2 March 2012 © 2011 The Authors

232 Clinical and Experimental Optometry © 2011 Optometrists Association Australia