Article Text

Download PDFPDF

Effect of phacoemulsification on facility of outflow
  1. Pouya Alaghband1,2,
  2. Laura Beltran-Agulló1,3,
  3. Elizabeth Angela Galvis1,
  4. Darryl R Overby4,
  5. Kin Sheng Lim1,2
  1. 1 Ophthalmology, St Thomas’ Hospital, London, UK
  2. 2 Academic ophthalmology, King’s College London, London, UK
  3. 3 Ophthalmology, Institut Català de la Retina, Barcelona, Spain
  4. 4 Department of Bioengineering, Imperial College London, London, UK
  1. Correspondence to Kin Sheng Lim, St Thomas’ Hospital, London SE1 7EH, UK ; shenglim{at}


Purpose Phacoemulsification has been shown to reduce intraocular pressure (IOP). The mechanism of action is thought to be via increased trabecular outflow facility. However, studies on the relationship between phacoemulsification and outflow facility have been inconsistent. This study intended to examine the change in electronic Schiotz tonographic outflow facility (TOF) and IOP measurements following phacoemulsification.

Methods Patients who were due to undergo a standard clear corneal incision phacoemulsification with intraocular lens (IOL) implantation, at St Thomas’ Hospital, were invited to participate in this study. IOP was measured using Goldmann’s applanation tonometer, and TOF was measured by electronic Schiotz tonography at baseline and at 3, 6 and 12 months postoperatively.

Results Forty-one patients were recruited. Tonography data for 27 patients were reliable and available at all time points. Eleven cases had primary open angle glaucoma and cataract, while 16 patients had cataract only. Mean IOP reduced at every time point postoperatively significantly compared with baseline. TOF improved significantly after cataract extraction at all time points (baseline of 0.14±0.06 vs 0.18±0.09 at 3 months, P=0.02 and 0.20±0.09 at 6 months, P=0.003, 0.17±0.07 µL/min mmHg at 12 months, P=0.04). Five contralateral eyes of patients with cataracts only who did not have any intraocular surgery during the follow-up period were used as comparison. Their IOP and TOF did not change significantly at any postoperative visits.

Conclusion This is the first study using electronic Schiotz tonography with documented anterior chamber depth and gonioscopy after modern cataract surgery (CS) with phacoemulsification and IOL implantation. We demonstrated that phacoemulsification increases TOF and this fully accounts for the IOP reduction following CS.

ISTCRN registration number ISRCTN04247738.

  • Phacoemulsification
  • cataract surgery
  • glaucoma
  • outflow facility
  • tonography

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

View Full Text

Statistics from


  • Contributors PA: conception, design, drafting the article, collecting data, drafting the article, analysis and interpretation of data. LBA: collecting data, drafting the article, EG: collecting data, drafting the article, revising the article. DRO: revising the paper, analysis of data and revising the article. KSL: conception, design, revising the article and interpreting data. PA, DRO and KSL were involved in revising the article critically for important intellectual content. All authors read and approved the final revision.

  • Funding KSL was supported by a funding at the National Institute for Health Research, Guy’s and St Thomas’ Hospitals Biomedical Research Centre, London, UK.

  • Competing interests None declared.

  • Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.

  • Ethics approval Guy’s and St Thomas Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Linked Articles

  • At a glance
    Keith Barton James Chodosh Jost B Jonas