Ординатура / Офтальмология / Английские материалы / Step by Step Laser in Ophthalmology_Bhattacharya_2009
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7.Shields CL, Shields JA, DePotter P, Khetrapal S. Transpupillary ThermoTherapy in management of choroidal melanoma. Ophthalmology 1996;116;1509-11.
8.Shields CL, Shields JA, Cater J, et al . Transpupillary thermotherapy for choroidal melanoma.Tumour control and visual results in 100 consecutive cases. Ophthalmology 1998; 105:581-90.
9.Subramanium ML, Reichel E.Current indications of transpupillary thermotherapy for treatment of posterior segment disease.Current Opin Ophthalmol 2003;14:155-58.
10.Verma L, Tewari HK, et al. Transpupillary thermotherapy in subfoveal choroidal neovascular membrane secondary to age-related macular degeneration.Indian J Ophthalmol 2004;52:35-40.
CHAPTER 6
Photocoagulation in
Peripheral Retinal
Degenerations
and Tears
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PERIPHERAL RETINAL DEGENERATIONS
Peripheral retinal degenerations include lattice degeneration, paving stone degeneration and pigmentary degeneration etc.
Indications
1.History of retinal detachment in fellow eye
2.Morphological progression of peripheral retinal degeneration
3.Appearance of subjective symptoms like lightning flashes
4.Aphakic eye.
Contraindications
1.Asymptomatic lattice degeneration without a) hole and b) history of retinal detachment in fellow eye
2.Presence of even a shallow retinal detachment around the peripheral retinal degeneration.
General Steps
1.Explain the procedure.
2.Signing informed consent.
3.Mydriasis—Maximum pupillary dilation with Tropicamide (1%) and Phenylephrine (10%) starting 2 hour prelaser.
4.Anesthesia—1 drop topical Proparacaine HCl (0.5%) few minutes prior to photocoagulation. Peribulbar inj Lignocaine HCl in nystagmus and uncooperative patient.
5.Comfortable sitting on revolving stool.
6.Steady fixation—Apply head strap and adjust fixation target.
PHOTOCOAGULATION IN PERIPHERAL RETINAL 61 
7.Insert appropriate Laser contact lens—Goldmann 3-mirror. It is available with argon/diode bonded antireflective coating for photocoagulation.
8.Room illumination—Darkened/semi darkened.
9.Adjust slit-lamp beam.
Photocoagulation Technique Proper
1.Parameters
•Spot size—500-800 µm
•Exposure—0.1-0.2 sec.
•Power—*400-600 mW
•Pattern—Usually solitary, linear, single row and interrupted (interval = ½ of spot size)
2.The photocoagulation burns should be placed at least 1 DD (Disc diameter) i.e. 1500 µm away from the border of the peripheral retinal degeneration (Fig. 6.1A).
3.Initially, most **anterior margins are photocoagulated.
4.If the degeneration is extensive or considerable vitreous traction is present, initial single row of coagulation may be reinforced by double row of linear, interrupted coagulation (Fig. 6.1B).
Postlaser Advice
1.Cycloplegic, e.g. Cyclopentolate Hcl (1%)-3 times daily × 7-10 days.
2.Topical steroid- 3-4 times daily × 7-10 days.
Complications
1.Retinal detachment
2.Choroidal rupture
3.Vitreous hemorrhage
*More peripherally located degenerations are treated with higher power. **Anterior most retinal periphery is more difficult to visualize and the patient may cooperate better during the earlier stage of laser session.
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Fig.6.1A: Schematic drawing—Photocoagulation of peripheral retinal (lattice) degeneration (linear, single row, interrupted and interval = ½ of spot size) in superotemporal periphery. Note 2 retinal holes within the lattice
Fig.6.1B: Schematic drawing—Initial single row of coagulation is reinforced by double row of linear, interrupted laser coagulations
Follow-up
1 week →3 weeks →3-6 months
RETINAL BREAKS
Retinal breaks include atrophic retinal holes (without operculum), retinal holes with free floating or attached operculum and retinal tears.
PHOTOCOAGULATION IN PERIPHERAL RETINAL 63 
Indications
1.History of retinal detachment in fellow eye.
2.Very shallow retinal detachment with little subretinal fluid SRF).
3.Presence of vitreous traction on the margin of break or operculum.
4.Presence of vitreous or preretinal hemorrhage with a break.
5.Persistent symptomatic (Lightning flashes, shower of black spots etc.) retinal break.
Contraindications
1.Asymptomatic inferior break with pigmented margins.
2.Absence of history of retinal detachment in fellow eye.
General Steps
1.Explain the procedure.
2.Signing informed consent.
3.Mydriasis—Maximum pupillary dilation with Tropicamide (1%) and Phenylephrine (10%) starting 2 hour prelaser.
4.Anesthesia—1 drop topical Proparacaine HCl (0.5% ) few minutes prior to photocoagulation. Peribulbar inj Lignocaine HCl in nystagmus and uncooperative patient.
5.Comfortable sitting on revolving stool.
6.Steady fixation—Apply head strap and adjust fixation target.
7.Insert appropriate Laser contact lens—Goldmann 3-mirror. It is available with argon/diode bonded antireflective coating for photocoagulation.
8.Room illumination—Darkened/semi darkened.
9.Adjust slit-lamp beam.
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Photocoagulation Technique Proper
Parameters
•Spot size—500-1000 µm
•Exposure—0.2-0.5 sec.
•Power—*400-600 mW
•Pattern—Usually solitary, linear, single row and interrupted (interval = ¼ of spot size) burns to surround the anterior, posterior and lateral margins of the break.
–Initially, most** anterior margin of the break is photocoagulated (Fig. 6.2A) followed by photocoagulation of easily visible posterior margin (Fig. 6.2B)
–In presence of considerable vitreous traction, initial single row of coagulation must be reinforced by single or double row of linear, interrupted coagulation on all margins (Fig. 6.3).
–The laser beam should avoid the pathway of vitreous attachment to the operculum.
–The operculum of horseshoe tear should not be photocoagulated.
Postlaser Advice
1.Cycloplegic, e.g. Cyclopentolate HCl (1%)-3 times daily × 7-10 days.
2.Topical steroid- 3-4 times daily × 7-10 days.
*Preretinal hemorrhage or pigment clumps present near the break or operculum absorbs more laser energy. So, in those situations less power is required.
**Anterior most retinal periphery is more difficult to visualize and the patient may cooperate better during the earlier stage of laser session.
PHOTOCOAGULATION IN PERIPHERAL RETINAL 65 
A |
|
B |
Figs 6.2A and B: (A) Initially, most anterior margin of the break is photocoagulated (single row of linear, interrupted and interval = ¼th of spot size coagulations); (B) Next, posterior of the break is photocoagulated (single row of linear, interrupted and interval = ¼th of spot size coagulations)
Fig.6.3: Initial single row of coagulation must be reinforced by single or double row of linear, interrupted coagulation on all margins in presence of considerable vitreous traction. The laser beam should avoid the pathway of vitreous attachment to the operculum. The operculum of horseshoe tear should not be photocoagulated
Complications
1.Extension of retinal break
2.Retinal detachment
3.Choroidal rupture
4.Vitreous hemorrhage.
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Postlaser Follow-up
1 week →3 weeks →3-6 months
BIBLIOGRAPHY
1.American Academy of Ophthalmology. Management of posterior vitreous detachment, retinal breaks and lattice degeneration.Preferred Practice Pattern.San Francisco, CA: American Academy of Ophthalmology 1998. (I).
2.Gholam A. Peyman, Donald R. Sanders, Morton F. Goldberg (eds). Principles and Practice of Ophthalmology (1st Indian Ed.).Philadelphia:W.B.Saunders Company, 1987: 1118.
3.L’esperance FA Jr. Ophthalmic Lasers. (3rd edn.). St. Louis: CVMosby Co. 1989:291-301.
CHAPTER 7
Photocoagulation
in Peripheral
Chorioretinal Tumors