We write to congratulate Dr Walland and Professor Thomas on their excellent review.1 We agree with the conclusion that clear lensectomy for the management of a patient with an asymptomatic non-progressive narrow angle appearance is inappropriate, particularly in the presence of a patent laser peripheral iridotomy (LPI).
We feel that at the other end of the acute angle closure spectrum, where there is significant cataract in the presence of narrow angle, peripheral anterior synechiae (PAS) and elevated pressure, cataract surgery may well be indicated. This will improve visual acuity and render negligible for the life of the patient the possibility of developing acute angle closure.
Between these two clinical scenarios there is a zone where clinical judgment must be exercised on a case-by-case basis.
In our view, in the presence of a narrow angle configuration, established PAS and elevated pressure, there may be a case to remove the lens if the clinician observes further PAS formation or a progressive rise in intraocular pressure. This presumes that there is a patent LPI. Further, gonioplasty is an option that may be considered.
In the setting of fellow eyes at risk of acute primary angle closure (APAC), the therapeutic options include gonioplasty, pilocarpine and lens extraction. It is reasonable to try gonioplasty in this setting. Pilocarpine may have significant compliance issues associated with multiple dosing and poor tolerance. Apart from this, by stimulating ciliary muscle contraction, pilocarpine loosens the ciliary zonules. This may lead to anterior displacement of the lens iris diaphragm, which in turn can lead to aggravation of the APAC by further shallowing of the anterior chamber.2 In addition, pilocarpine also increases resistance to flow through the pupil (pupil block)3 and may set up a pressure differential between posterior and anterior chambers. This can lead to the anterior bowing of the iris, resulting in progressive PAS formation.
When gonioplasty has failed and in the presence of a patent LPI, clear lensectomy is a reasonable option in the setting of suspected deterioration, either in the form of new PAS or uncontrollable intraocular pressure, to minimize the risk of APAC and primary angle closure glaucoma.
In reference to our earlier work,4 we would like to clarify that APAC was managed with evidential protocols in the first instance, including medical and laser treatment. We only performed cataract surgery as secondary treatment, once primary treatment had failed. In our experience, phaco-emulsification in these patients was successful in rapidly creating quiet, normotensive and anatomically stable eyes. This suggests that there may be a role for this form of surgery as a reasonable alternative to the traditional approach of guarded filtration surgery in such patients.5
We share the authors' concerns regarding recent pseudoscientific discussions that are proposing clear lens extraction as a potential cure-all for a condition as complex as primary angle closure glaucoma. In light of this we applaud the authors for bringing a much-needed evidence-based critique to the debate, and would encourage our colleagues to maintain an analytical approach to managing this important condition.