<<Glaucoma Conference>> Laser Surgery for Glaucoma 2013.10.18 R4.이민영/Ap.이나영

Laser surgery for Glaucoma Laser iridotomy (LI) Laser Peripheral Iridoplasty (LPI) Argon Laser Trabeculoplasty (ALT) Selective Laser Trabeculoplasty (SLT)

Laser iridotomy (LI)

History 1956 – Xenon arc laser (Meyer-Schwickerath) thermal damage to cornea & lens 1960s – Ruby red stimulated red laser 1970s – continuous wavelength Argon laser 1980s – Nd:Yag laser Nd (Neodymium):Yag laser laser 로 방수가 post. .chamber 에서 ant. chamber 로 바로 이동하도록 해줌.

Indications Acute primary angle closure Fellow eye of acute primary angle closure 50% risk of APAC at fellow eye in 5yrs Chronic angle closure with OHT or PAS Narrow or occludable angle etc. Complete/Incomplete closure of previous iridotomy To widen the angle for trabeculoplasty

Contraindications Poor cooperation Severe corneal edema Very shallow chamber PAS at 360 degree Secondary synechiae e.g. Uveitis, NVG, ICE syndrome

Techniques Preparations Control inflammation (topical steroids) Constrict pupil (topical pilocarpine 1-4%, 3 times over 10minutes before procedure) Adequate anesthesia Prevent IOP spikes (topical apraclonidine / brimonidine, 30min. before & immediately after) Prevent IOP spikes -안압이 높을 경우 oral acetazolamide 를 쓸수도 있다. Adequate anesthesia 는 점안 마취로 충분하지만 Retrobulbar anesthesia- 협조가 안되거나 안진이 있는 환자의 경우.

Techniques Choice of position avoid 12 o/c position ( d/t gas bubble) superonasal >> superotemporal ( d/t position of macula) between middle 2/3 and peripheral 1/3 iris crypts or thinned iris inf. position for silicon oil filled eye crypt: 움. 특히 두꺼운 iris 에서는 iris crypts or thinned iris 를 겨냥해야 한다. silicon oil filled eye 에서는 기름이 위로 뜨기 때문에 아래쪽에 구멍을 낸다.

epithelium & endothelium Techniques Argon laser Nd:YAG laser Mechanism photocoagulation (thermal) photodisruption (mechanical) Iris pigments brown > blue same Inflammation common less Pupil change Damage to cornea epithelium & endothelium endothelium Bleeding IOP spikes similar ( 30 ~ 35% ) Iridotomy closure 진한 홍채의 실질이 레이저를 잘 흡수하므로 연한 홍채보다 시술이 용이하다. 야그레이저는 색소상피가 열을 흡수하여 조직이 파괴되는 것이 아니라 전기 기계적으로 파괴된다.

Techniques Burns and laser setting for argon iridotomy -Contraction : 낮은 출력, 큰 spot size, 긴 노출시간 갈색홍채는 200mW로 시작 옅은홍채는 300mW로 시작 -짙은 홍채는 penetration burn 대신 punch burn 으로 (charring 피함) Contraction Stretch Punch Penetration Cleanup Spot size(µm) 500 200 50 Duration(sec) 0.5 0.01~0.02 0.05~0.2 0.1~0.2 Power(mW) 200~400 800~1500 600~1200 300

Techniques Pulsed ND: Yag Laser iridotomy spot size : 50 µm (usually fixed) Duration : 12 nano seconds (usually fixed) Energy level : 2.6~20 mJ Pulses : 1-3 pulses per burst

Techniques Combination of Argon laser & ND:Yag laser 1st – iris hump by Argon laser 2nd – iridotomy by ND:Yag laser lower bleeding risk (coagulation of iris blood vessels) lower iris pigment dispersion Yag laser 만으로 했을 때보다 bleeding risk 가 적고, 야그레이저 만 하면 홍채가 절개되기 전에 홍채 색소가 분산되어서 ( 절개부위를 막을 수 있으므로.) 안좋다.

Techniques 2-stage Argon Laser iridotomy technique For brown irides Stage 1- spot size: 50µm; duration:0.1 sec; power: 1000 mW Stage 2- spot size: 50µm; duration:0.1 sec; power: 400-600 mW For blue irides Stage 1 - spot size: 500µm; duration:0.1 sec; power: 200-300 mW Stage 2- spot size: 50µm; duration:0.1 sec; power: 500-700 mW For brown irides – stage 1 에서 몇번에 걸쳐 연속적으로 광응고 시키면 직경 500 마이크로 미터의 분화구가 생기고 색소 상피에 도달하면 홍채색소가 구름처럼 나타난다. 이때부터 레이저 강도를 낮추어 남은 조직을 제거. For blue irides – 엷게 착색되어 실질이 레이저 에너지를 잘 흡수하지 ㅇ낳아 어려움. 후선 stage 1으로 황갈색 부위를 만든후 stage 2 의 세기로 남은 실질 기질을 제거한다.

Techniques 2-stage ND:Yag Laser iridotomy technique 1. spot size : 50 µm (usually fixed) 2. Energy level : 5-15 mJ 3. Duration : 12 nano seconds (usually fixed) 4. Pulses : 1-3 pulses per burst spot 사이즈는 대개 고정 되어 있고 에너지는 5-15 mJ 범위 내에서 홍채 실질기질과 색소상피에 동시에 구멍을 만들게 된다. 노출시간 도 대개 12 나노 second 로 고정되어 있고 burst 당 1-3 회로 조사 횟수를 조절해서 사용한다.

Postoperative management Topical apraclonidine 1% (or brimonidnie) Topical steroids (4 times/day) IOP mesurements at 1-2 hours after surgery if high, Oral acetazolamide reassessment on day 1 IOP Gonioscopy 안압이 떨어지고, 환자의 불편감이 사라진 후, Gonioscopy 를 시행하여 pilocarpine 으로 인한 축동효과가 사라진 후에도 angle 이 충분히 넓어져 있는지 확인해야 한다.

Complication 1) IOP spikes PG & analogues highest after 1 hr (lasts 3hours) correlate with total energy Topical apraclonidine 1% (or brimonidnie) 2) Anterior uveitis disruption of Blood-aqueous barrier Topical steroids for 3-5 days 혈액 방수 장벽이 파괴되면서 PG 와 그 유사물질이 방수로 분비되고 전방각에 혈장과 섬유소가 침착되기 때문에. 횟수보다는 총 에너지에 상관이 있는 것으로 보이며,

Complication 3) Iridotomy site closure more common in ALI iris pigments & debris topical Pilocarpine for 4~6wks Lens capsule/vitreous thorugh iridotomy site 4) Corneal damage epithelium/endothelium high energy 레이저 에 의하여 각막 상피 또는 내피에 손상이 있을 수 있는데, 국소적으로 각막의 상피와 내피가 광응고 된것은 후유증 없이 빨리 치유되는 편이지만 다량의 에너지를 사용하는 것은 피하는 것이 좋다.

Complication 5) Hyphema ND:Yag laser only : 67% Combination : 4 ~ 17 % Ocular compression with contact lenses 6) Cataract progression of cataract : rare closer iridotomy site to iris margin 7) Retinal damage rare, but avoid macular area

Complication 8) Optical aberrations monocular diplopia ghost image haloes or spots Appropriate positions / Color lenses 이런 증상은 절개부위가 위눈꺼풀 에 의해 부분적으로 가려지면 나타날 수 있고, 완전히 노출되거나 완전히 가려지면 증상이 나타나지 않는다. 윗눈거풀에 완전히 가려지도록 수술 부위를 선택해야 하고, 그래도 안되면 컬러렌즈를 사용할 수도 있다.

Laser Peripheral Iridoplasty (LPI)

Introduction Another effective procedure to open the closed angle. series of laser burns of low power large spot size long duration to the Extreme peripheral iris

Indications Angle closure Adjunctive procedure Acute Chronic Corneal edema, shallow chamber, severe inflammation Chronic Plateau iris Lens related Choroidal effusion Nanophthalmos, CRVO, scleral buckling, PRP, etc.. Adjunctive procedure Laser trabeculoplasty Laser iridotomy Plateau iris - characterized by closing of the anterior chamber angle secondary to a large or anteriorly positioned ciliary body that mechanically alters the position of the peripheral iris in relation to the trabecular meshwork. Lens related – phacomorphic, zonular weakness Choroidal effusion- effusio 이 lens iris diaphragm 을 앞쪽으로 밀어서 angle 을 막을 수 있다. 하지만 chamber 가 flat 하여 endothelial damage 가 예상되거나, corneal edema , opacity 가 너무 심한 경우에도 할 수 없다./

Technique Preopreative managements topical anesthesia 1 ~ 2 drops of Pilocarpine ( 2% or 4%) Topical a-2 agonist (apraclonidine or brimonidine)

Technique Argon laser settings Power Avoid PAS areas spot size : 500 ㎛, 0.5 sec, 200 ~ 400 mW contracting burns Power increase : insufficient contraction decrease : Gas bubble, pop sound, iris pigment dispertion (over heating) Avoid PAS areas Limited treatments also effective in acute attack Avoid contiguous pattern Extreme peripheral 너무 밀접하게 붙여서 레이저를 하면 안된다.

Postoperative management Topical a-2 agonists apraclonidine brimonidine Topical steroids 4 times/day x 5 days Gonioscopy follow up Pilo 의 효과가 떨어졌을 때쯤 Gonioscopy follow up 을 하고 필요하면 추가 레이저를 한다.

Complications Mild iritis (m/c) Focal PAS IOP spikes Endothelial burns Pigmented iris marks Iris atrophy Mydriasis Recurrence of angle closure Corectopia - Corectopia is the displacement of the eye's pupil from its normal, central position.[1] It may be associated with high myopia or ectopia lentis.[2] Medical or surgical intervention may be indicated for the treatment of corectopia

Argon Laser Trabeculoplasty (ALT)

Enhancement of aqueous outflow facility Mechanical theory(laser trabecular tightening) Scar formation  tighten the collagenous ring in the outflow pathway  TM이 당겨지고 쉴렘관이 넓어져 유출 증가 Physiological changes in the trabecular cells Increased phagocytic properties(TM 내피세포) 광응고되지 않은 주위의 TM에서 보상성 구조적 변화 Biochemical ECM changes 광응고되지 않은 TM에서 방수유출에 저항이 적은 새로운 ECM을 생성한다 혈액-방수 장벽의 파괴로 안압이 하강되는 것이 아니다

Indications for ALT Primary open angle glaucoma Secondary open angle glaucoma Pigmentary glaucoma Exfoliative glaucoma

Contraindications for ALT Angle recession Uveitis glaucoma Aphakia Increased episcleral venous pressure IOP > 35 mmHg Previous 360° ALT treatment Young patients (age<40) Hazy media : corneal edema of flare, etc. Near total angle closure(PAS)

Operative technique Preoperatively 1% apraclonidine or a hyperosmotic agent Not necessary to constrict the pupil Intraoperatively Topical anesthesia 3-mirror Goldman lens or Ritch trabeculoplsty lens Spot size 50㎛, duration 0.1 sec, power 0.5~1.0W Location of the burns : junction of the non-pigmented and pigmented meshwork Blanching to the tissue or small bubble formation Density of the burns : 8 / clock hour 180 ° at a time, 50 burns per session Postoperatively Monitor the IOP at least the first hour after ALT 1% apraclonidine immediately 2% or 4% pilocarpine, topical or systemic carbonic anhydrase inhibitor Topical steroid drops for the first 4days

Outcomes POAG Pigmentary glaucoma Exfoliation glaucoma Success rate : 72.5~97% By 5years, only 50% of individuals remain successful Advantageous for patients that have limited access to medications and poor follow-up Pigmentary glaucoma Reduction of IOP ALT is recommended in all patients with pigmentary glaucoma(especially young pt) Exfoliation glaucoma Success rates 50% after 5years

Complication Pressure elevation Peripheral anterior synechiae Risk factor All 360° of TM is treated in one sitting Posterior placement of burns Retreatment (after 360 ° TM ALT) Tx. : 1% apraclonidine, 2% or 4% pilocarpine, topical or systemic CA inhibitors, hyperosmotic agents Peripheral anterior synechiae In Glaucoma Laser Trial, 46% of eyes demonstrated PAS Risk factor : high power levels, placement of burns (far too posterior and close to the iris root) Uveitis, hyphema, corneal burns, syncope

Selective Laser Trabeculoplasty (SLT)

Introduction To reduce the energy level directed on the TM Selective photothermolysis to pigmented structures 532 nm frequency-doubled Q-switched Nd:YAG laser 3ns pulse, 400㎛ beam diameter Prevent damage of adjacent cells and tissues ALT SLT

Mechanism of SLT ALT : disruption and coagulative necrosis SLT No scarring or coagulative damage Only cracking of intracytoplasmic pigment granules Injury to pigmented TM cells → release of chemoattractants & recruit monocytes → macrophages clear pigment granules from the TM → exit the eye via Schlemm’s canal

Indications for SLT Steroid-induced glaucoma Open-angle glaucoma Prior ALT has failed Uncontrolled IOP Alternative when surgery is contraindicated Steroid-induced glaucoma Resulting IOP 10mmHg at 6 months post-SLT Pseudoexfoliation(PXF) glaucoma IOP was reduced less in the PXF group than in the POAG group But 64% success rate in the PXF group

Technique Preoperatively 0.5% apraclonidine or brimonidine In uveitic eyes, timolol Topical anesthesia 3-mirror Goldman goniolens or Latina SLT lens, Ritch trabeculoplsty lens Spot size 400㎛, duration 3ns, power 0.8mJ(0.2~1.7 mJ depending on the pigmentation) Density of the burns : 50-100 adjacent and nonoverlapping spots over 180-360° TM Avoid Sampaolesi’s line and pigmented corneal endothelial cells

Technique Usually done over 180° 90° SLT vs. 180° SLT : equally effective Spread of free radicals → stimulation of low-grade inflammation → clean-up of other parts of the TM → facilitation of aqueous outflow After 6 weeks, inadequate IOP reduction → retreatment Multiple treatment is possible : additional 15% IOP reduction Postoperatively Indomethacin 0.1% x3 for 10days Dexamethasone-neomycin x4 for 7days Prednisolone acetate 1% x4 for 5-7 dyas

Outcomes 4~6 week period is required for the full effects of SLT Demonstrated a decreased in IOP at 2 weeks post SLT : no need for IOP screening until 3 months Reduce the need for antiglaucoma medications 0.46~0.55 No. of eyedrops in the SLT group 1.45~1.64 in the medical treatment group (P<0.001)

Complication Fewer side effect than ALT Complications Energy delivery of only 1% of ALT Complication rate : 4.5%(SLT) vs. 34%(ALT) No PAS Complications Greater AC reaction 1hour after SLT IOP increase Pigment storm in pigmentary glaucoma or PXF glaucoma Low energy setting (0.4~0.6mJ) Fewer applications Limit treatment to a smaller area Blurred vision(0.8%), corneal edema(0.8%), corneal lesion(0.8%)

Reference Glaucoma [Shaarawy, Tarek / Saunders / 2009] Shields' textbook of glaucoma [Allingham, R. Rand. Shields, M. Bruce / Wolters] 녹내장 개정 5판, 한국녹내장학회