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Cataract Surgery | Mar 2009

How to Treat Cataract and Coexistent Corneal Opacity

Trypan—blue-assisted cataract surgery is a useful surgical option in these cases, with phacoemulsification as the preferred technique.

Corneal opacification is a major cause of blindness in the developing and the developed world. In a sizeable portion of cases, associated age-related cataracts contribute to poor visual acuity. Although corneal transplantation with cataract extraction and IOL implantation has been the preferred method for treating cases with corneal scars and coexisting age-related cataract,1,2 some patients attain good vision with cataract surgery alone.

For example, one-eyed patients who may be high-risk candidates for combined corneal transplantation and cataract extraction procedures may achieve adequate vision after cataract surgery alone. However, successful surgery may be difficult because the surgeon has only suboptimal visualization of the intraocular structures.

Allograft corneal transplantation combined with extracapsular cataract extraction and IOL implantation has been the preferred method for treating cases of corneal opacification and coexisting cataract. However, the scarcity of donor corneas, risk of graft failure, graft infection, secondary glaucoma, and suture-related problems after this combined procedure necessitate the use of alternative surgical techniques to manage patients with partial corneal opacification and cataract.

Various surgical phacoemulsification techniques have been described for use in patients with coexisting cataract and partial corneal opacification, including intraoperative use of trypan blue dye,3 creation of pupillary sphincterotomies,4 and use of endoillumination.5,6 This article gives a brief overview of these techniques.

PTK
When corneal opacification is restricted to the anterior 100 µm of the cornea, a phototherapeutic keratectomy (PTK) may be attempted before cataract surgery. PTK is performed in a standard fashion, using the 193-nm excimer laser.7 The surgical technique comprises mechanical epithelial debridement followed by ablation in the central 5-mm zone. In cases with band keratopathy, a surgical blade may be used for mechanical removal of calcium plaques. Methylcellulose may then be used as a masking agent for irregular surfaces before ablation. Adequacy of the depth of ablation is assessed with regular intraoperative visualization of the cornea between laser bursts or by intraoperative slit-lamp examination.

Refractive changes following PTK can be variable; significant myopic or hyperopic shifts may occur. Subsequent cataract surgery may be performed 6 weeks after PTK using a standard surgical technique.

INTRAOPERATIVE USE OF TRYPAN BLUE
Cases with deep or full-thickness corneal scars are not amenable to treatment with PTK. In such situations, the corneal opacity may impede visibility—even in the presence of an adequate fundus reflex. Intraoperative steps, such as capsulorrhexis, nuclear emulsification, residual cortex removal, and IOL implantation are dependent upon the ability to visualize the capsular bag anatomy. In these cases, trypan–blue-assisted cataract surgery is a viable option; however, at least part of the cornea must be clear to allow visualization of the stained capsule and nucleus after capsulorrhexis creation.

Trypan blue 0.01% is safe when applied to the corneal endothelium,8,9 and capsular staining has been previously documented for management of mature white cataracts and cataracts with coexisting corneal opacities.3,10 The intraoperative use of trypan blue dye enhances visibility of the anterior capsule and delineation of the lenticular morphology. It also aids in visualization of the capsulorrhexis margin during phacoemulsification. Tables 1 and 2 describe the surgical technique for performing phacoemulsification in a case with partial corneal opacification with the help of trypan blue dye.

PUPILLARY ENLARGEMENT
In cases with cataract and coexisting partial corneal opacification, cataract surgery with pupillary enlargement helps to create an optical window. A sphincterotomy or an optical iridectomy may be used. In either treatment, the size of the pupil is enlarged in the direction of the nonopacified cornea. This may confer long-lasting ambulatory vision after cataract surgery in patients with a central corneal opacity. It is especially relevant in patients who are bilaterally blind or in eyes with severe deep corneal stromal vascularization. It may be used as an alternative to a corneal triple procedure.

ENDOILLUMINATION
If commonly used capsular dyes, such as trypan blue and indocyanine green, are ineffective for staining the anterior capsule, endoillumination may be used for improving intraoperative visualization. Nishimura et al5 described a technique of inserting an endoillumination probe through a corneal paracentesis created at the limbus using a 19-gauge slit knife. Oshima et al6 reported the successful use of a transconjunctival chandelier illumination system for performing cataract surgery in patients with corneal opacification. In this technique, a self-retaining, 25- or 27-gauge chandelier illumination fiber (Synergetics, Inc., O'Fallon, Missouri) is inserted into the vitreous cavity transconjunctivally through the pars plana at the beginning of surgery.

DISCUSSION
Patients with nebulomacular corneal opacities and visually debilitating cataract may become ambulatory with cataract surgery alone. Here, phacoemulsification is the preferred surgical technique because it allows early visual rehabilitation. However, a successful phacoemulsification may be difficult in cases of corneal opacity because the surgeon has suboptimal visualization of the lenticular morphology.

Important surgical steps, such as capsulorrhexis, nuclear emulsification, removal of residual cortex, and foldable IOL implantation are dependent upon the ability to visualize the capsular bag anatomy. Capsular staining with trypan blue dye facilitates the delineation of the lenticular morphology and aids in performing the capsulorrhexis in cases with corneal opacities. Trypan–blue-assisted phacoemulsification in selected cases of corneal opacity with cataract is safe and feasible, both as a primary therapeutic option in cases where penetrating keratoplasty is not promising or possible and as an interim procedure if the patient is awaiting keratoplasty, conferring early visual rehabilitation. Other surgical techniques, such as the use of endoillumination and creation of pupillary sphincterotomy, have been described for the effective management of these cases.

Vishal Jhanji, MD, is a clinical research fellow at the Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Victoria, Australia. Dr. Jhanji states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +61 3 9929 8368; fax: +61 3 9662 3959.

Rasik B. Vajpayee, MS, FRCS(Ed), FRANZCO, is a Professor of Ophthalmology and Head of the Corneal Unit at the Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Victoria, Australia. Dr. Vajpayee states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +61 3 9929 8368; fax: +61 3 9662 3959.

  1. Inoue Y. Corneal triple procedure. Semin Ophthalmol. 2001;16(3):113-118.
  2. Shimmura S, Ohashi Y, Shiroma H, Shimazaki J, Tsubota K. Corneal opacity and cataract: triple procedure versus secondary approach. Cornea. 2003;22(3):234-238.
  3. Bhartiya P, Sharma N, Ray M, Sinha R, Vajpayee RB. Trypan blue assisted phacoemulsification in corneal opacities. Br J Ophthalmol. 2002;86(8):857-859.
  4. Sinha R, Sharma N, Vajpayee RB. Visual outcome of cataract surgery with pupillary sphincterotomy in eyes with coexisting corneal opacity. BMC Med. 2004;7(2):10.
  5. Nishimura A, Kobayashi A, Segawa Y, Sugiyama K. Endoillumination-assisted cataract surgery in a patient with corneal opacity. J Cataract Refract Surg. 200;29(12):2277-2280.
  6. Oshima Y, Shima C, Maeda N, Tano Y. Chandelier retroillumination-assisted torsional oscillation for cataract surgery in patients with severe corneal opacity. J Cataract Refract Surg. 2007;33(12):2018-2022.
  7. Ayres BD, Rapuano CJ. Excimer laser phototherapeutic keratectomy. Ocul Surf. 2006;4(4):196-206.
  8. Norn MS. Preoperative trypan blue vital staining of corneal endothelium; eight years' follow-up. Acta Ophthalmol. 1908;58:550-555.
  9. Kothari K, Jain SS, Shah NJ. Anterior capsular staining with trypan blue in mature and hypermature cataract: a preliminary study. Indian J Ophthalmol. 2001;49:177-180.
  10. Dada VK, Sharma N, Sudan R, Sethi H, Dada T, Pangtey MS. Anterior capsule staining for capsulorhexis in cases of white cataract: comparative clinical study. J Cataract Refract Surg. 2004;30(2):326-333.
  11. Vajpayee RB, Sharma N, Dada T, Pushker N. Optical sector iridectomy in corneal opacities. Cornea. 1999;18(3):262-264.

 

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