Lasers in Primary Angle Closure Glaucoma.pptx

Role of different lasers to treat angle closure glaucoma

1. Dr Abeer Rehman Ophthalmology Resident Al- Shifa Trust Eye Hospital, Rawalpindi TREATMENT OPTIONS FOR PACG AFTER FAILED LASER PROCEDURES

2. CASE SCENARIO A 60 y/o man with a history of PACG underwent laser peripheral iridotomy (LPI) in both eyes a month ago. He returns for follow-up with persistent elevated intraocular pressure in the right eye (28mmHg). Gonioscopy reveals appositional closure of the angle in the superonasal quadrant despite a patent LPI.

3. What are the indications for iridotomy and iridoplasty? Which procedure is typically performed first in acute angle closure glaucoma and why? How Do the mechanisms of action of iridotomy and iridoplasty differ? What are the potential complications of iridotomy and iridoplasty? What are the alternative treatment options for angle closure if laser procedures are not successful? QUESTIONS

4. LASER PERIPHERAL IRIDOTOMY We create a full thickness hole I n peripheral iris allowing aqueous to drain from PC to TM provided the drainage system is functional. This eliminates high IOP due to pupillary block which is the most common mechanism of PACG.

5. Pre-treatment 1-4 % Pilocarpine is instilled. This causes miosis, reduces iris thickness and facilitates laser perforation. In the presence of corneal edema, topical glycerin 10% if available, systemic acetazolamide, I/V mannitol or oral hyperosmotic agents are given. IOP lowering drugs like alpha 2 agonists brimonidine/apraclonidine are given 1 hr prior to procedure and immediately afterwards to prevent or minimise early post laser IOP rise. Topical anesthetic instilled.

6. Procedure Iridotomy lens (Abraham 66D,Wise 103D) applied with coupling gel – Keeps eyelids open, minimises eye movements, provides magnification, improves visualization, reduces risks or corneal burns and increases power density by concentrating laser energy. We aim for iris crypt or area of thinning at periphery mostly 11 – 1 o clock which allows lesion to be covered by the upper eyelid. Some prefer 3 or 9 o clock position – (tear meniscus at the edge of upper lid creates a base up prism effect when overlapping the position of LPI and placement of LPI at 3 or 9 position might better serve the pt) Avoid 12 o clock position as air bubbles may occlude the iridotomy. If silicon oil or other tamponading fluids or gases are present, perform an inferior LPI. Successful penetration – gush of pigment debris. The number of shots required to produce an adequate iridotomy is variable. Optimal size 150-200um.

7. Post-treatment IOP lowering eye drops are given. If pt had high IOP pre-treatment or advanced glaucomatous damage oral AZM may also be given. Dexamethasoe 0.1% - initially every 10 mins for 30 minutes then hourly for 6-8 hours and then QID for 1 week. Check IOP 1 hour post LPI Check size and patency of iridotomy If iridotomy not patent, further tx can be applied after a few days, in urgent circumstances moving to a different site is a reasonable alternative. Gonioscopy should be repeated to document change in angle post iridotomy

8. COMPLICATIONS Bleeding from the iridotomy site can usually be stopped by gentle pressure applied to the eye with the contact lens. Visual disturbances e.g. glare, blurring, ghost images, halo, crescent are less likely to occur when the peripheral iridotomy is completely covered by the eyelid. Transient IOP elevation a few hours after the procedure is the most frequent early complication. Post operative inflammation is transient and mild, rarely resulting in posterior synechiae . Rare complications include cystoid macular edema and aqueous misdirection.

9. COMPLICATIONS cont. Iritis especially if excessive laser is applied or post laser steroid therapy is inadequate or in darker irides (including those due to prostaglandin derivative treatment. Corneal burns may occur if a contact lens is not used or if the AC is shallow, but these usually heal rapidly without sequelae. Localized lens opacities occasionally develop at the treatment site. There is some evidence that age-related cataract formation may be accelerated by iridotomy.

10. ARGON LASER PERIPHERAL IRIDOPLASTY LPI is performed to widen the AC angle by contraction of the peripheral iris away from the angle recess using thermal laser (diode, argon) A topical anesthetic is instilled One drop of each 1 % pilocarpine and 1% apraclonidine is instilled Via an iridotomy lens 1-2 burns per clock hour are applied to the periphery.

11. POST-PROCEDURE 1% apraclonidine is given (oral prophylaxis e.g. acetazolamide may be given if significant glaucomatous optic neuropathy is present) Topical ketorolac, prednisolone 1% or dexamethasone 0.1% 4x daily for a week is a common regime. Review is typically 1-2 hrs post laser, then after 1 week and subsequently depending on progress and glaucomatous damage – pt with significant glaucomatous neuropathy may need frequent review for the first few weeks to exclude an IOP spike.

12. INDICATIONS Acute primary angle closure – cornea edematous, or if topical tx and AZM have not broken an attack within an hour. Plateau iris syndrome Nanophthalmos Iris and ciliary body cysts COMPLICATIONS Mild iritis Corneal endothelial burns Transient elevation of IOP Post Operative synechiae of pupil Permanent pupil dilatation Peripheral iris atrophy ARGON LASER PERIPHERAL IRIDOPLASTY

13. CASE SCENARIO A 60 y/o man with a history of PACG underwent laser peripheral iridotomy (LPI) in both eyes a month ago. He returns for follow-up with persistent elevated intraocular pressure in the right eye (28mmHg). Gonioscopy reveals appositional closure of the angle in the superonasal quadrant despite a patent LPI .

14. DIFFERENTIALS Plateau Iris Syndrome Combined Mechanism Glaucoma Lens Induced Glaucoma Iridociliary cysts (pseudoplateau iris) Ciliary body tumor Posterior segment tumor Peripheral Anterior Synechae

15. PLATEAU IRIS SYNDROME T ypically female 30-50 years at presentation. Caused by anterior rotation of ciliary body or anomalous anterior iris root insertion on to the ciliary body itself. Peripheral iris is pushed forward leading to appositional closure of the angle. Plateau iris configuration describes an eye with narrow angle on gonioscopy, no LPI ,deep central anterior chamber. PIS – deep central anterior chamber and persistently narrow or closed angle on gonioscopy despite patent LPI

16. PLATEAU IRIS - ON EXAMINATION Slit lamp – Central anterior chamber depth is normal , although peripheral chamber can appear shallow, iris plane is typically flat Gonioscopy - angle is usually narrow or closed I ndentation gonioscopy reveals double hump sign/sigma sign (Physical presence of lens behind iris holds it centrally in position preventing posterior movement as a result a sinuous configuration results termed as sigma sign)

17. PLATEAU IRIS - DIAGNOSIS Gonioscopy Anterior segment OCT, UBM 1 – affected eyes display an anteriorly rotated ciliary body and may also have a shortened iris root with anomalous anterior insertion onto the ciliary body 2 - differentiate between plateaeu iris, pseudolateau iris, ciliary body tumor – important for proper therapeutic management.

18. PLATEAU IRIS - MANAGEMENT Medical – low dose pilocarpine induces contracture of the iris sphincter and ciliary body pulling the iris away from TM and widening the angle Laser Peripheral Iridotomy(there is usually a component of pupillary block when plateau iris exists- also, a plateau iris syndrome cannot truly be diagnosed until after LPI is performed.) A rgon laser peripheral iridoplasty ( ALPI) – if patient has persistent apposition of the iridocorneal angle or develops elevated IOP If these fail, trabeculectomy, drainage implantation or goniosynechialysis should be considered.

19. COMBINED MECHANISM GLAUCOMA Despite a patent iridotomy and synechial/appositional closure less than 180 – IOP still high Drainage system is also functionally impaired. Monitor patients response with long term drops Laser treatment to the drain itself or even drainage surgery

20. LENS INDUCED GLAUCOMA Hyperopic eyes – Short axial length, shallow anterior chamber,thick anteriorly sited lens Age-related increase in lens thickness and more anterior position of lens. L ens induced angle crowding can lead to acute or chronic angle closure despite a patent LPI. ALPI has been used to manage acute phacomorphic angle closure with favourable results. Extraction of the abnormal lens in these conditions is ultimately the only way to definitively eliminate both angle-crowding and co-existing pupillary block. It I ncreases anterior chamber depth and angle width.

21. PERIPHERAL ANTERIOR SYNECHIAE LPI - l imited role in CACG, more than 180 degrees of PAS. GSL - removal of PAS of recent onset, long standing PAS likely to be associated with permanent TM damage. O n its own success in unlikely because it doesn’t address the underlying cause of synechial angle closure be it pupillary block or angle crowding hence it is often performed with other procedures. Permanent trabecular dysfunction - trabeculectomy

22. SUMMARY Post iridotomy follow up – check patency via transillumination. Repeat gonioscopy to see if a component of angle closure remains IOP Optic nerve functions Anterior segment OCT, UBM

23. SUMMARY OF TREATMENT OPTIONS FOR PACG Laser peripheral iridotomy Thermal laser peripheral iridoplasty Recent studes have show other surgical treatments that can be done for e.g. EAGLE trial found clear lens extraction to be a more successful and cost effective solution for PACG than LPI and can be considered 1st line. Another option is cataract surgery with endocyclophotocoagulation (ECP) which can simultaneously lower IOP and open the angle through combined mechanism of lens removal and contracture of the ciliary processes. Goniosynechialysis Currently there is no evidence that cataract extraction with ECP or GSL is superior to cataract extraction alone in the treatment of angle closure. I ncisional surgery – Trabeculectomy or glaucoma drainage devices with or without goniosynechialysis