Dr. Minu sasikumar, M19267, Dr. Anthrayos C V Kakkanatt,
Dr. Anju Kuriakose, Dr. Geethu Gopinath, Dr. Anu F Anand
ABSTRACT
Laser can be tried for treatment of lid, adnexa, conjunctiva & ocular pathologies like I&D of hordeoluminternum/ externum/small lid abcess, conjunctval papillae/cyst, cauterization of blood vessels of primary pterygium/corneal pathology/graft failure, wart (filiform), molluscum, skin tag, colloid milium, syringoma, melanocytic nevus, capillary haemangioma etc. A retrospective study of case records of 970 patients treated with slit-lamp 532/1064 nm double frequency Nd-YAG laser(532/1064nm) under local/surface anaesthesia for these pathologies with a minimum follow up of 6 months were analyzed. Age varied from 14 -72 yrs (average 38 yrs),females 62%,males 38%.Out of 970 eyes 124 eyes undergone repeat laser, so excluded from analysis. The case distribution were: wart 18%,molluscum 16%, I&D 15%, cautery of blood vessels 9%,papillae/cyst 8%,others 36%.Patients tolerance was good & no serious complications occurred. Laser therapy is a simple alternative repeatable OP procedure for extra ocular pathologies.
INTRODUCTION
capsular opacification after cataract surgery and to create a peripheral iridotomy in patients with narrow angles or angle-closure glaucoma.
AIM:To study the use of Nd YAG laser in the treatment of ocular pathologies and its outcome
METHODOLOGY:A retrospective case study of 970 patients who attended ophthalmology OPD at Jubilee Medical College from January 2014 to October 2016 was included in the study. All patients who presented with ocular pathology were included in the study .
INCLUSION CRITERIA: All patients in the age group of 14 to 75 years who attended ophthalmology OPD at Jubilee Medical College from December 2016 to June 2017 were included in the study .Patient was followed up for a period of 6 months with weekly visit in the first one month and thereafter monthly review for the next 6 months.
Exclusion criteria: Patients who required repeat laser or showed no resolution of the pathology was excluded from the study.
PROCEDURE: Allpatients attending the ophthalmology OPD was subjected to detailed evaluation including visual acuity, slit lamp evaluation, intraocular pressure recording and fundus evaluation.
Patients with ocular pathology is given surface anaesthesia(lignocaine jelly/drops)or local infiltration of lignocaine and seated in front of slit lamp. Using slit lamp 532/1064 nm double frequency enhanced Nd YAG laser is applied to the lesion. Lesions over eyelid are cleaned with betadine.Pterygium cases are given post laser topical steroid and antibiotic for a period of 1 week.
SAMPLE SIZE:A total of 970 eyes were studied out of which 124 were excluded from the study as they required repeat laser
RESULTS:
Retrospective analysis of 970 eyes with ocular pathology was studied out of which 124 were excluded as they required repeat laser.
Age distribution showed maximum incidence in the age group of 31 to 40 years
2.SEX DISTRIBUTION
Sex distribution showed more incidence of conjunctival ,lid and orbital lesions among females
3.DISEASE DISTRIBUTION
Nd YAG laser was attempted for warts ,pterygium,molluscum ,papillae and cysts.
4.COMPLICATIONS
Patients with pterygium developed redness in the immediate post laser period,they were started on topical antibiotic and steroid which disappeared after 1 week .All patients were evaluated weekly for the first month and thereafter monthly for the next 6 months. 124 eyes showed recurrence and thereby excluded from study
DISCUSSION
The host medium for Ndyag laser is yttrium aluminium garnet (yag = y3 al5 o12) with 1.5% trivalent neodymium ions (nd3+) present as impurities.The (nd3+) ions occupy the lattice sites of yttrium ions as substitutional impurities and provide the energy levels for both pumping and lasing transitions.When an (nd3+) ion is placed in a host crystal lattice it is subjected to the electrostatic field of the surrounding ions, there is the so called crystal field. The crystal field modifies the transition probabilities between the various energy levels of the nd3+ ion so that some transitions, which are forbidden in the free ion, become allowed. The length of the Nd: yag laser rod various from 5cm to 10cm depending on the power of the laser and its diameter is generally 6 to 9 mm the laser rod and a linear flash lamp are housed in a elliptical reflector cavity.Since the rod and the lamp are located at the foci of the ellipse, the light emitted by the lamp is effectively coupled to the rod.The ends of the rod are polished and made optically flat and parallel.The optical cavity is formed either by silvering the two ends of the rod or by using two external reflecting mirrors.One mirror is made hundred percent reflecting while the other mirror is left slightly transmitting to draw the output .This system is cooled by either air or water circulation.This laser system has two absorption bands (0.73 m and 0.8 m).Laser transition takes place between two laser levels at 1.06 mm.Opticalpumping mechanism is employed.
Output characteristics : laser output is in the form of pulses with higher repetition rate.Xenon flash lamps are used for pulsed output nd: yag laser can be operated in cw mode also using tungsten-halide incandescent lamp for optical pumping.Continuous output powers of over 1kw are obtained
These lasers typically emit light with a wavelength of 1064 nm, in the infrared1 .Transitions near 946, 1120, 1320, and 1440 nm can also be attained. Nd:YAG lasers can operate in both pulsed and continuous wave mode. Pulsed Nd:YAG lasers are typically operated in the Q-switching mode.In this mode, output powers of 250 megawatts and pulse durations of 10 to 25 nanoseconds have been achieved2.The high-intensity pulses are efficiently frequency doubled to generate laser light at 532 nm, or higher harmonics at 355, 266 and 213 nm.
Nd:YAG absorbs mostly in the bands between 730–760 nm and 790–820 nm.
The amount of the neodymium dopant in the material varies according to its use. For continuous wave output, the doping is significantly lower than for pulsed lasers. The lightly doped CW rods can be optically distinguished by being less colored, almost white, while higher-doped rods are pink-purplish.
Other common host materials for neodymium are: YLF (yttrium lithium fluoride, 1047 and 1053 nm), YVO4 (yttrium orthovanadate, 1064 nm), and glass.
The laser is less efficiently absorbed by endogenous melanin and thus result in fewer epidermal adverse effects especially while treating dark skinned individuals.
Moskalik et al studied the efficacy of facial skin cancer treatment with high-energy pulsed neodymium and Nd:YAG lasers and found it to be effective method to treat facial skin cancer of stages T(1-2)N(0)M(0), and resulted in acceptable cosmetic results3.
Our study included 152 eyes with wart over eyelid which was successfully treated with laser.
Nd:YAG lasers are used in ophthalmology for posterior capsular opacification, and for peripheral iridotomy in patients with acute angle-closure glaucoma, where it has superseded surgical iridectomy. Frequency-doubled Nd:YAG lasers (wavelength 532 nm) are used for pan-retinal photocoagulation in patients with diabetic retinopathy
It is used extensively in the field of cosmetic medicine for laser hair removal and the treatment of minor vascular defects such as spider veins on the face and legs. Recently used for Dissecting cellulitis of the scalp4.
Omi T et al studied the outcome of recalcitrant molluscumcontagiosum treated with Nd YAG laser wherein they applied a single shot from a 585 nm pulsed dye laser to each lesion (3 mm, 300 ms, 8.0 J/cm(2)).Fifteen children comprised the study subjects, 11 boys and 4 girls, 3-5 years of age (mean 4.2 yr) with recalcitrant molluscumcontagiosum. Lesions were counted at baseline, and counted again at 1 week post-treatment and followed for up to 3 months thereafter.A single treatment of molluscumcontagiosum lesions with the pulsed dye laser successfully cured even recalcitrant lesions with no recurrence on follow up, and was well tolerated by the young subjects5.
In our study 135 eyes with molluscumcontagiosum was treated with Nd YAG laser .Youngest patient was aged 14 years .A single treatment showed no recurrence of lesion when followed up for a period of 6 months.
Nakamura k et al studied the usefulness of Er ;YAG laser for pterygium. The removal of pterygium was accomplished under topical anesthesia with a laser output approximate range from 50 to 100 shots. Complications such as corneal erosion or thinning of the sclera were not observed. However, recurrence was seen in the 3 retreatment casesand thereby concludedthat Er:YAG laser system may be a clinically useful tool as a laser surgical knife for ocular tissue6
In our study we applied Nd YAG laser was applied to 186 eyes with pterygium and patients were followed up for a period of 6 months and no incidence of recurrence was noted .This was based on the coagulative property of Nd YAG laser
Amir HosseinSiadat et al studied the incidence of colloid milium caused by exposure to intense sunlight and treated it successfully with Er-YAG laser7
Kilmer et al studied the effect of frequency-doubled Q-switched Nd:YAG laser in the treatment of epidermal pigmented lesions.Frequency-doubled Q-switched neodymium (Nd):YAG laser (532 nm, 2.0-mm spot size, 10 nanoseconds) was used in removing benign epidermal pigmented lesions with a single treatment. Forty-nine patients were treated for multiple lentigines (n = 37), for cafe au lait macules (n = 7), and for miscellaneous lesions (n = 5). Treatment areas were divided into four quadrants, irradiated with fluences of 2, 3, 4, or 5 J/cm2 and evaluated at 1- and 3-month intervals following treatment.He concluded frequency-doubled Q-switched Nd: YAG laser (532 nm) to be safe and effective in treatment of benign epidermal pigmented lesions8.
Levy JL et al conducted a similar study on the treatment of individual café au lait macules with the Q-switched Nd:YAG9
Grossman et al also conducted similar study on the effect of Nd YAG laser in the treatment of cafe au lait spots and found it to be effective in its management10
Nd YAG laser is able to create a coagulation effect at a depth of 5-6 mm thereby useful in treating moderately deep large calibre vessels and feeding reticular veins.3 and 5 mm spot sizes are suitable for superficial lesions and larger 5 and 7 mm spot size for thicker or deeper ones .Pulse duration should be based on vessel size of each lesion 11,12.
304 eyes with miscellaneous conditions like feeder vessels ,hyperpigmented scars etc were successfully treated with Nd YAG laser .
This is an ongoing study where all the 846 eyes are being monitored monthly for recurrence and complications. Till now patient tolerance was good and no recurrence is being reported.124 eyes required repeat laser due to poor regression and was thereby excluded from the study
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