Visual Axis Opacification (VAO)

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Visual axis opacification (VAO) after cataract surgery is commonly encountered in children, at a higher rate than that in adults. It may lead to amblyopia and hinders with the achievement of visual rehabilitation in pediatric cataract. For this reason, media assessment (checking fundal glow with direct ophthalmoscope) in the postoperative follow-up period becomes an important tool for early detection of any media opacification.

Disease Entity

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Disease

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Etiology

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Risk Factors

Researchers have analyzed various risk factors predisposing for PCO development, even despite PCCC and AV such as:

• Younger age of child: More intense inflammation has been noted in children operated at a younger age.6,7

• Surgical trauma

• Smaller capsulorrhexis size : An anterior capsulorrhexis should be adequately sized while performing cataract surgery. A 5 mm opening in anterior capsulorrhexis is considered as adequate.

• Traumatic cataracts: Traumatic cataracts after cataract extraction lead to more PCO formation than congenital or developmental cataracts.

• Uveitic cataracts : Postoperative inflammation may result into faster an higher rate of PCO formation in uveitic cataracts. Capsular phimosis / anterior capsular contraction syndrome may result as early as few weeks in these cases.8

• IOL biomaterial : Studies comparing the acylic material prove that hydrophilic acrylic material accelerates PCO formation more than hydrophobic material.9 Heparin surface coating on polymethyl methacrylate (PMMA) i.e. Heparin surface modified IOLs (HSM-IOLs) also cause less PCO formation and are used for uveitic cataracts.10

(Hydrophilic acrylic IOL > PMMA IOL> hydrophobic IOL)

• IOL design: A capsular bend with sharp and square optic edge induce contact inhibition to migrating LECs, thus reducing PCO formation.11

• Extent of cortical cleanup: Vigorous cortical cleanup should be avoided as it may cause remnant lens matter to migrate to the posterior capsule during the surgery and LECs may rapidly proliferate to form VAO.

• Site of IOL fixation: In the bag fixation of posterior chamber IOL after PCCC and AV is currently the most accepted surgical choice to achieve excellent IOL centration and good visual outcomes. Other options of IOL fixation which are equally effectively in reducing PCO formation include: optic capture12 of IOL behind the posterior capsule opening and bag-in-the-lens13 fixation. Sulcus fixation of IOL may also result in higher PCO formation than bag fixation.

Besides these, poorly centred anterior capsulorrhexis in the bag may also accelerate PCO formation if it does not cover all the edges of IOL


General Pathology

Lens epithelial cells (LECs) proliferate and form PCO.

Pathophysiology

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Primary prevention

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Diagnosis

  1. Screening - Distant direct Ophthalmoloscopy - Red reflex is tested for detection of visual axis opacification

History

The symptoms may vary. Children, unlike adults, often report their symptoms late.

  • Vision deprivation. If vision improved after previous cataract surgery, VAO may lead to vision deprivation.
  • Deviation or strabismus
  • Photophobia / inability to open eyes in bright light

Physical examination

Ocular examination - w

Signs

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Symptoms

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Clinical diagnosis

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Diagnostic procedures

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Laboratory test

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Differential diagnosis

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Management

Video 1

General treatment

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Medical therapy

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Medical follow up

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Surgery

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Surgical follow up

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Complications

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Prognosis

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Additional Resources

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References

1. McDonnell PJ, Zarbin MA, Green WR. Posterior capsule opacification in pseudophakic eyes. Ophthalmology. 1983 Dec;90(12):1548–53. 2. Blomstedt G, Fagerholm P, Gallo J, Philipson B. After-cataract in the rabbit eye following extracapsular cataract extraction--a wound healing reaction. Acta Ophthalmol Suppl. 1987;182:93–9. 3. Wormstone IM. Posterior capsule opacification: a cell biological perspective. Exp Eye Res. 2002 Mar;74(3):337–47. 4. Knight-Nanan D, O’Keefe M, Bowell R. Outcome and complications of intraocular lenses in children with cataract. J Cataract Refract Surg 1996; 22:730–736 5. Kuhli-Hattenbach C, Lüchtenberg M, Kohnen T, Hattenbach L-O. Risk Factors for Complications After Congenital Cataract Surgery without Intraocular Lens Implantation in the First 18 Months of Life. Am J Ophthalmol. 2008 Jul 1;146(1):1–7.e1. 6. Hosal BM, Biglan AW. Risk factors for secondary membrane formation after removal of pediatric cataract. J Cataract Refract Surg. 2002 Feb 1;28(2):302–9. 7. Peterseim MW, Wilson ME. Bilateral intraocular lens implantation in the pediatric population. Ophthalmology. 2000 Jul;107(7):1261–6. 8. Nishi O, Nishi K. Intraocular lens encapsulation by shrinkage of the capsulorhexis opening. J Cataract Refract Surg. 1993 Jul;19(4):544–5. 9. Heatley CJ, Spalton DJ, Kumar A, Jose R, Boyce J, Bender LE. Comparison of posterior capsule opacification rates between hydrophilic and hydrophobic single-piece acrylic intraocular lenses. J Cataract Refract Surg. 2005 Apr;31(4):718–24. 10. Lundvall A, Zetterstrom C. Cataract extraction and intraocular lens implantation in children with uveitis. Br J Ophthalmol. 2000 Jul;84(7):791–3. 11. Nishi O, Nishi K, Sakanishi K. Inhibition of migrating lens epithelial cells at the capsular bend created by the rectangular optic edge of a posterior chamber intraocular lens. Ophthalmic Surg Lasers. 1998 Jul;29(7):587–94. 12. Intraocular lens optic capture in pediatric cataract surgery [Internet]. [cited 2018 Oct 28]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6090124/ 13. Bag-in-the-Lens Cataract Surgery [Internet]. American Academy of Ophthalmology. 2015 [cited 2018 Oct 28]. Available from: https://www.aao.org/clinical-video/bag-in-lens-cataract-surgery 14. Atkinson CS, Hiles DA. Treatment of Secondary Posterior Capsular Membranes With the Nd:YAG Laser in a Pediatric Population. Am J Ophthalmol. 1994 Oct 1;118(4):496–501. 15. Gilbard SM, Peyman GA, Goldberg MF. Evaluation for cystoid macu- lopathy after pars plicata lensectomy-vitrectomy for congenital cataracts. Ophthalmology 1983;90:1201–1206. 16. Hoyt CS, Nickel B. Aphakic cystoid macular edema; occurrence in infants and children after transpupillary lensectomy and anterior vitrectomy. Arch Ophthalmol 1982;100:746–749. 17. Brady KM, Atkinson CS, Kilty LA, Hiles DA. Cataract Surgery and Intraocular Lens Implantation in Children. Am J Ophthalmol. 1995 Jul 1;120(1):1–9. 18. Khokhar SK, Pillay G, Dhull C, Agarwal E, Mahabir M, Aggarwal P. Pediatric cataract. Indian J Ophthalmol. 2017 Dec;65(12):1340–9. 19. Vasavada AR, Trivedi RH. Role of optic capture in congenital cataract and intraocular lens surgery in children. J Cataract Refract Surg. 2000 Jun;26(6):824–31.