Ocular phototherapy

1. Aziza ahmed hassan
Assistant professor of ophthalmology
NILES

2. Phototherapy means: ‘light or radiant energy-
induced treatment.' the scope of phototherapy will
be limited to
Photocoagulation
Thermotherapy
photodisruption
photoablative
Photodynamic therapy (PDT)
Photobiomodulation
These modalities are frequently used to treat a
wide variety of ocular diseases.

4.  Lasers have become the exclusive source of light or
radiant energy for all applications of phototherapy in
treatment of ocular diseases.
 properties of laser such as
monochromatic wavelength
coherent waves
non-divergence
provide high-energy source that can be easily
manipulated.
 Argon and krypton laser have wavelengths within the
visible spectrum (400–700nm). Nd-YAG laser and
Co2 laser emit infrared wavelengths. Excimer laser is in
the ultraviolet range.

5. 10-12
10-10
10-8
10-6
10-4
10-2
100
102
104
106
108
x-rays
gamma rays
Ultra-
violet Infrared Radar
Radio
waves
Electric
waves
The Electromagnetic Spectrum
Ionizing
Radiation
Wavelength (cm)
Laser wavelengths are usually in the Ultraviolet,
Visible or Infrared Regions of the Electromagnetic
Spectrum.

6. The optical spectrum
Laser light is nonionizing and ranges from the:
 ultra-violet (100 - 400nm)
 visible (400 - 700nm), and
 infrared (700nm - 1mm).
EM Spectrum
Laser

7.  Depending on the
Wavelength
Intensity
Duration of exposure
 Tissues can either absorb the energy
(photocoagulation, thermotherapy, and PDT) or undergo
ionization (photodisruption).
 Ocular phototherapy applications for treatment of
ocular diseases are based on principles of absorption of
energy.
 However, the tissue reaction to absorbed energy vary
from coagulation or denaturation (photocoagulation),
tissue heat (thermotherapy), or release of singlet
oxygen (PDT).

8. •The WL is determined by the active medium of
each particular laser
* Active medium can consist of:
1. Gas (Argon or CO2 laser)
2. Liquid (dye laser)
3. A solid (ruby or yttrium-aluminum-garnet crystal
laser)

9. Laser tissue Interaction
Different types of lasers react differently with tissue
Interaction depends on:
•The wavelength of the laser
•Power density and exposure time
•Optical and thermal property of the
tissue being irradiated
•Laser beam size
•If exposure is CW or pulsed wave
radiation

10.  The light or radiant energy can be easily applied to
ocular surface or delivered to the intraocular
structures through the pupil.
 For phototherapy to be effective, the energy has to
be absorbed by tissues or more specifically by
naturally occurring pigment within them.
 Based on distribution and absorption spectrum of
the pigment, laser source of a particular
wavelength can be selected to achieve tissue-
specific damage.

11.  Xanthophyll, which is confined to the macula, has a
narrow absorption spectrum confined to blue
wavelengths.
 Hemoglobin mostly absorbs blue, green, and
yellow wavelengths.
 Melanin offers least specificity as it has the
broadest absorption spectrum that extends across
blue, green, yellow, and red wavelengths.

12.  In tissues or tumors that lack natural pigment such
as a melanotic melanoma or choroidal
haemangioma, dyes with narrow absorption
spectrum can be injected intravenously that act as
focal absorbent of laser energy after they have
preferentially localized within the tumor. Such
targeted phototherapy is the underlying basis of
PDT. Commonly used photosensitizer in treatment
of ocular tumors include indocyanine green and
verteporphin (Visudyne).

13.  Photocoagulation is the thermal denaturation of
tissues. Tumors containing hemoglobin and
melanin can readily absorb argon or krypton laser
wavelengths and therefore considered for
treatment of diabetic retinopathy,HTN
Retinopathy, Retinal tears, ocular tumors,etc.
 The role of tumor photocoagulation is limited
because of concerns for tumor dissemination,
tumor recurrences, and availability of more
effective treatments.

16.  Retinal tumors
 Small retinoblastoma < (3mm x 2.0mm) can
be treated with photocoagulation mostly to the
surrounding retina in an attempt to cut off the
vascular supply rather than direct
photocoagulation because of concerns for
dissemination retinoblastoma cells into the
vitreous cavity, photocoagulation is used very
infrequently.

19.  Retinal capillary haemangioma have been
treated with photocoagulation.
Photocoagulation is applied as a combination
of direct and feeder vessel occlusion
technique.
The control rates vary between 75 and 90%.
Photocoagulation is particularly effective in
controlling small extrapapillary tumors (1.5mm
or smaller.

22. Choroidal tumors
 Choroidal melanoma and choroidal haemangioma
have been treated in the past with
photocoagulation.
 As a result of concerns for the lack of efficacy
(haemangioma) and recurrences (melanoma) over
the long term, photocoagulation has been replaced
by PDT (haemangioma) and radiation plaque
therapy (melanoma).

23.  Choroidal haemangioma

25. Osterhuis introduced the concept of transpupillary
thermotherapy (TTT) in 1995.
 During TTT, the tumour is heated to a temperature
of 60–65°C by means of an infrared diode laser
applied via the pupil. The rise in temperature
causes cytotoxicity.

27.  TTT is generally used for relatively small
tumors without associated vitreous or
subretinal seeds and is used in conjunction
with adjuvant chemotherapy.
 Larger tumors are at greater risk for
complications such as focal iris atrophy and
focal paraxial lens opacity because they
require more intense therapy as compared
with smaller tumors.

28. Fundus appearance immediately
after thermotherapy of a 1mm
retinoblastoma (a). Four weeks
later, the tumor is replaced by a
choriod retinal scar (b)

29.  TTT was used as a primary therapy for ‘small'
choroidal melanocytic lesions (melanomas
<4mm in height or high-risk naevi with or
without documented growth).
 Complications of the TTT such as local tumour
recurrence. epiretinal membrane, retinal
traction, retinal detachment, vascular
occlusions, and absolute wedge-shaped
scotoma have been reported.

32.  TTT can be a convenient and cost effective
treatment option in the management of small
choroidal metastatic tumors (thickness
<3.5mm) providing local control.
 choroidal haemangioma. Complications such
as cystoid macular oedema, preretinal
fibrosis, focal iris atrophy, and retinal
vascular occlusion can be avoided with the
use of PDT while achieving equally high
response rate.

33. External recurrence following TTT.
Fundus photograph showing fibrotic
membrane with fine retinal
neovascularization at the treated site
of small choroidal melanoma following
three sessions.

34.  PDT is a non-thermal, photo biochemical
procedure that offers site-specific vascular
occlusion and tumour destruction with
minimal damage to adjacent neural
structures. The safety of PDT has been
established treatment of choroidal
neovascularization (CNV),angiod streaks and
corneal neovascularizations.

39.  Eyelid tumors
PDT is used for a variety of inflammatory conditions ,
premalignant and malignant tumors including basal
cell carcinoma (BCC).
PDT has also been used for treatment of periocular
BCC in a small number of cases.
 Conjunctival tumors
PDT may be an alternative treatment for ocular
surface squamous neoplasia, particularly with diffuse
presentation.

40.  Retinal tumors
PDT with verteporfin causes fewer side effects as it
offers site-specific tumour destruction while
sparing surrounding structures.
 Retinal capillary haemangioma: the tumour
response to PDT was transient, the tumors
showed sustained response to PDT including
reduced perfusion, shrinkage, and resolution
of subretinal fluid. Visual acuity improved or
remained stable in the majority of eyes.

42. Circumscribed choroidal haemangioma
 Various treatment modalities including argon laser
photocoagulation, cryotherapy, external beam radiotherapy,
proton beam radiotherapy, episcleral plaque radiotherapy,
and TTT have been tried with varying degrees of success in
stabilizing or improving visual acuity.
 The major limitation of these treatment modalities is the risk
of damage to the overlying retina.
 Tumour regression and resolution of subretinal fluid in
diffuse choroidal haemangioma (Sturge–Weber Syndrome) is
generally treated with low-dose radiotherapy or proton beam
radiotherapy.

44. Choroidal melanoma
 Although experimental studies have demonstrated
evidence of melanoma regression following PDT,
attempts at treatment of choroidal melanoma with
PDT in the clinical setting have been disappointing
 Choroidal metastases
PDT is effective in treatment of symptomatic
choroidal metastases that have failed chemotherapy.

46.  Retinal vascular occlusion
 Optic neuropathy
 Vitreous hemorrhage
 Tractional retinal detachment

47. low myopia (up to 6D)
and low hyperopia
(up to 3D)

48. lamellar dissection with the micro keratome
refractive ablation with the excimer laser
Intra LASIK/Femto-LASIK or
All-Laser LASIK ( corneal flap is made with
Femto second laser micro keratome)

49. Suction Ring Microkeratome Flap Removed
LASIK Flap replaced Post operative

53. Cruciate pattern Circular pattern

54. Laser peripheraLiridotomy
Laser iridopLasty (GoniopLasty)
ND:YAG Laser iridotomy : Q-switched Nd:YAG lasers (1064 nm)
2–3 shots/burst using approximately 1–3 mJ/burst
opening of at least 0.1 mm

55. Thank you