Biomedical subjects

Henry H L Chan

Publications and source records attributed to Henry H L Chan.

At least 19 recordsLinked to original sources

PubMed2007

Radiosurgery versus carbon dioxide laser for dermatochalasis correction in Asians.

BACKGROUND AND OBJECTIVES: Carbon dioxide (CO(2)) laser and radiosurgery are techniques commonly employed in oculoplastic surgery. However, there is no literature comparing their results in blepharoplasty. STUDY DESIGN/MATERIALS AND METHODS: Twenty Chinese patients with dermatochalasis underwent radiosurgery in one upper eyelid and CO(2) laser in the contralateral eyelid. Intraoperative time, hemorrhage, and pain control were assessed. Subjects were evaluated at postoperative 1 hour, 1 week, 1 month, and 3 months for hemorrhage and wound healing by a masked assessor. RESULTS: All patients reported minimal pain with either technique. A significantly shorter operative time was achieved with CO(2) laser, with better intraoperative hemostasis. There was no significant difference in postoperative hemorrhage and wound swelling between radiosurgery and CO(2) laser. No significant intraoperative complications were noted. CONCLUSIONS: Both radiosurgery and CO(2) laser are equally safe and effective for upper lid blepharoplasty. CO(2) laser achieves shorter operative time with superior intraoperative hemostasis.

Aged↗

PubMed2007

An animal study of the effects on p16 and PCNA expression of repeated treatment with high-energy laser and intense pulsed light exposure.

BACKGROUND AND OBJECTIVE: Non-ablative skin rejuvenation treatments that involve the use of laser/light sources together with cooling devices have gained much popularity in recent years due to the lack of down time that is associated with them. One important but neglected issue is long-term safety. Does the repeated use of non-ablative skin rejuvenation lead to photoaging? Are we creating another sun-bed phenomenon? Recently, we performed an in vitro study to examine the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines, and found that sub-lethal laser damage could increase DNA damage, which led to an increase in p16 expression. Our objective was to assess the cutaneous effect of repeated exposure to high-energy lasers and intense pulsed light sources on male Institute of Cancer Research (ICR) mice. STUDY DESIGN/MATERIALS AND METHODS: Twenty-eight male ICR mice were divided into four groups. Other than the control group, all groups received either laser (585 nm pulsed dye laser or 1,320 nm Nd:YAG laser) or intense pulsed light (IPL) treatment. All four groups were anesthetized with a mixture of Hypnorm/Dormicum before treatment. The animals were irradiated twice a week for 6 months. Signs of toxicity such as mortality and weight loss were checked once a week. Skin tumor formation was evidenced by lesions of greater than 1 mm in diameter that persisted for 2 weeks. At the end of the 6 months, the expression of proliferating cell nuclear antigen (PCNA) and p16 in the mouse skin was determined by immunohistochemical staining and immunoblotting using specific monoclonal antibodies for mouse PCNA and p16. The results were expressed as mean +/- standard error of the mean (SEM). Statistical difference was assessed by multiple ANOVA. A P-value of <0.05 was considered to be significant. RESULTS: At the end of the 6 months, none of the animals had developed any signs of toxicity such as mortality or weight lost. There was no evidence of tumor formation. There were significant elevations of p16 and PCNA in all treated groups as compared to the control group (ANOVA P < 0.05). This particularly applied to the group that was treated with the 1,320 nm Nd:YAG laser. CONCLUSION: The repeated use of high-energy laser and intense pulsed light source did not cause any toxicity in mice. The changes in p16 and PCNA imply that further studies are necessary to consider the implications of repeated exposure to longer wavelength radiation in human skin.

Animals↗

PubMed2006

Effects of unsteady fixation on multifocal electroretinogram (mfERG).

PURPOSE: To investigate the effect of unsteady fixation on the multifocal electroretinogram (mfERG) measurement in normal subjects. METHODS: The mfERGs of 20 subjects with normal vision (mean age=23.5 years) were recorded with different levels of voluntary eye movements made to mimic unsteady fixation. Subjects were required to move their fixation regularly every 2 s between the center and the ends of a fixation cross, so that 51.2% of the time fixation was at the center and 12.2% of the time it was at each end of the fixation cross. Four different conditions were performed: central fixation (without voluntary eye movements) and with 2 degrees, 4 degrees and 6 degrees magnitude of unsteady fixation. First-order kernel mfERG findings are presented. RESULTS: Analysis of the ring responses indicated that the central mfERG amplitude was most affected by unsteady fixation. There was significantly reduced amplitude for 4 degrees unsteady fixation and as expected, this reduction became larger with 6 degrees unstable fixation. However, there was no significant effect on the center hexagon amplitude for 2 degrees unsteady fixation. The amplitudes of the ring-2 responses were only affected in the 6 degrees unsteady fixation condition. No significant change in implicit time was found for any level of unsteady fixation. CONCLUSION: These results suggest that mfERG amplitude is not substantially affected if fixation is maintained within the central stimulus hexagon. We conclude that, for patients with poor fixation, the accuracy of mfERG results may be difficult to interpret and the use of a fixation-monitoring system is desirable for ideal measurement. The depth of depression at the blind spot area may be another useful parameter to interpret the accuracy of mfERG results in patients with poor fixation.

Adult↗

PubMed2006

Changes of retinal functions following the induction of ocular hypertension in rats using argon laser photocoagulation.

BACKGROUND: Electroretinography (ERG) provides a longitudinal monitoring of pathological changes in retina. Scotopic threshold response (STR) of ERG was shown to reflect inner retinal activity and is particularly useful in the evaluation of inner retinal changes in ocular hypertension models. Recently, STR was demonstrated to be attenuated after the induction of ocular hypertension using injection of hypertonic saline into episcleral veins which indicates an impairment of retinal function. However, little is known on the changes of retinal function in an ocular hypertension model induced by laser photocoagulation at episcleral veins and limbal veins. METHODS: Ocular hypertension was induced unilaterally using laser photocoagulation at episcleral veins and limbal veins in adult Sprague-Dawley rats. Intraocular pressure was monitored and the number of retinal ganglion cell loss was counted across the 8-week experimental period. The animals were dark adapted overnight and flash ERGs were measured before the laser treatment, 5 and 8 weeks after treatment. The changes of STR, scotopic negative response, a-wave and b-wave were analysed. RESULTS: Approximately 1.6-fold elevation of intraocular pressure was induced in the experimental eyes and 3% retinal ganglion cell loss per week was found. The amplitude of STR was significantly attenuated which indicates an impairment of inner retinal activities. There was also a reduction of scotopic negative response, a-wave and b-wave after the induction of ocular hypertension. CONCLUSION: The laser-induced ocular hypertension model in the present study produced a substantial reduction of retinal functions. Understanding the characteristic of pathological changes is crucial for further study using this model.

Animals↗

PubMed2006

Glaucoma detection is facilitated by luminance modulation of the global flash multifocal electroretinogram.

PURPOSE: To investigate the variation of retinal electrophysiological function in glaucoma by using the global flash multifocal electroretinogram (mfERG) stimulation with altered differences in the stimulus luminance of the multifocal flashes, in an attempt to alter the levels of inner retinal contributions. METHODS: The mfERG was assessed with a visual stimulus in steps of four video frames, which consisted of 103 scaled hexagonal elements followed by a dark frame, global flash, and dark frame. The localized luminance difference was set at 96%, 65%, 49%, or 29% stimulus contrast. Thirty subjects with glaucoma and 30 age-matched normal subjects were recruited for visual field and mfERG measurements. RESULTS: This stimulus induces complex local first-order responses with an early direct component (DC) and a later induced component (IC). The luminance-modulated response functions of the DC and IC responses showed markedly different behavior. The peripheral IC showed a linear dependence on luminance difference, whereas the peripheral DC was saturated for higher luminance differences. This saturation became less obvious in subjects with glaucoma, mostly because of greater reduction of the response amplitude in the mid luminance-difference level. An "adaptive index" was calculated from the luminance-difference dependence of the peripheral DC, and it showed a sensitivity of 93%, with a specificity of 95% for differentiating normal from glaucomatous eyes, and also had a significant correlation (r = 0.58) with the glaucomatous visual field defect. CONCLUSIONS: The peripheral DC luminance-modulated response function is altered by the adaptive mechanism that is induced by the global flash; the reduction of the adaptive index may thus relate to an abnormal adaptive mechanism, presumably due to inner retinal damage. Glaucoma appears to produce large reductions of the adaptive index which correlate with field defects.

Adult↗

PubMed2006

Melanopsin-expressing retinal ganglion cells are more injury-resistant in a chronic ocular hypertension model.

PURPOSE: To investigate the survival of melanopsin-expressing retinal ganglion cells (mRGCs) after the induction of chronic ocular hypertension. METHODS: Intraocular pressure (IOP) was elevated in adult Sprague-Dawley rats using an argon laser to photocoagulate the episcleral and limbal veins. IOP was measured with a calibrated tonometer and monitored for a period. Seven days before the animals were killed, a piece of sterile foam soaked with gold fluorescent dye was placed onto the superior colliculus (SC) to label the SC-projecting retinal ganglion cells (scRGCs) retrogradely. mRGCs were visualized by free floating immunohistochemistry on whole-mounted retinas. The number of surviving scRGCs and mRGCs were counted on flatmounted retinas. The branching pattern of dendrites and soma size of mRGCs were examined. RESULTS: An approximately 1.7-fold increase of IOP and a significant loss of scRGCs were found in experimental eyes after laser photocoagulation. However, no significant cell loss or morphologic changes on mRGCs and their dendrites after the induction of chronic ocular hypertension are noticed over a 12-week period. CONCLUSIONS: Although the degeneration of retinal ganglion cells (RGCs) is a major concern in glaucomatous damage, the findings show that mRGCs are less susceptible to death after the induction of chronic ocular hypertension. This result indicates that mRGCs carry some unique properties that are different from those of other subpopulations of RGCs. The immunohistochemistry approach can be used to distinguish easily these mRGCs from other subtypes. This method provides a useful tool to investigate their injury-resistant properties that are informative for the development of effective neuroprotective treatment for glaucoma.

Animals↗

PubMed2006

Unilateral mediothoracic exanthem: a variant of unilateral laterothoracic exanthem.

We report the cases of a 4-year-old Chinese boy and a 33-year-old Chinese man with prodromal constitutional symptoms followed by eruption of small, painless, erythematous, papular lesions on relatively medial aspects of the anterior chest but not as far as the periflexural regions. Spontaneous remission was seen 2 and 3 weeks after rash onset in the child and the adult, respectively. We believe that the terms unilateral mediothoracic exanthem and unilateral thoracic exanthem are appropriate diagnostic labels. Such labels carry clinical significance as the patients can be reassured that although the rash may persist for weeks, final spontaneous remission with no complication is highly likely. Moreover, the risk of contagiousness is low, and we did not insist on isolation for prolonged periods.

Adult↗

PubMed2005

Effective and safe use of lasers, light sources, and radiofrequency devices in the clinical management of Asian patients with selected dermatoses.

BACKGROUND AND OBJECTIVES: The use of lasers, light sources, and radiofrequency devices in Asian patients differs from their use in Caucasians in several respects. STUDY DESIGN/MATERIALS AND METHODS: The disease spectrum is very different with pigmentary disorders being more commonly encountered in Asian populations. Asian skin, with its higher epidermal melanin content, is more likely to develop adverse reactions, especially post-inflammatory hyperpigmentation (PIH), following treatment. RESULTS AND CONCLUSIONS: The purpose of this article is to discuss the effective and safe use of lasers, light sources, and radiofrequency devices in the clinical management of Asian patients with selected dermatoses.

Acne Vulgaris↗

PubMed2005

Retinal stretching limits peripheral visual acuity in myopia.

Axial elongation of the myopic eye has the potential to stretch the retina, thereby reducing the sampling density of retinal neurons. Resolution acuity in the peripheral field of normal eyes is known to be sampling-limited, which suggests that retinal stretching in the myopic eye should have a direct effect on resolution acuity everywhere in the visual field except perhaps the fovea, which is usually optically limited. We tested this prediction that neural sampling density is reduced in myopic eyes by measuring resolution acuity for sinusoidal gratings in the fovea plus five peripheral locations in 60 myopic subjects exhibiting a wide range of refractive errors. Control experiments using a detection paradigm to provoke spatial aliasing verified that peripheral resolution was sampling limited. Retinal spatial frequencies of the grating stimulus were computed assuming Knapps' Law of visual optics, which ensures that retinal image size (in mm) is independent of refractive error when axial myopia is corrected by a spectacle lens located in the anterior focal plane of the eye. Results obtained at every retinal locus showed that resolution acuity declined linearly with magnitude of refractive error. Regression of the population data indicated that approximately 15 D of refractive error doubles the spacing between retinal neurons, thereby halving peripheral resolution acuity relative to the emmetropic eye. Several subjects also demonstrated sampling-limited performance in the fovea, which indicated that optical filtering by the eye's optical system failed to protect the fovea from aliasing artifacts of neural undersampling in these eyes. We conclude that stretching of the retina is a primary cause of reduced spatial resolution of the peripheral field, and occasionally of the fovea, in myopic eyes. Stretching appears to be locally uniform over the central +/-15 degrees of visual field but is globally non-uniform since the foveal region appears to stretch more than the globe itself.

Adult↗

PubMed2005

Electroacupuncture provides a new approach to neuroprotection in rats with induced glaucoma.

OBJECTIVES: To investigate, using multifocal electroretinogram (mfERG), the effect of electroacupuncture (EA) on retinal function in rats with experimental glaucoma. DESIGN AND SUBJECTS: Glaucoma was induced in the right eyes of 15 adult female Sprague-Dawley rats by laser photocoagulation for three quarters of the perilimbal and episcleral vessels. The left eye of each rat was used as the control. The animals were divided into 3 groups: no treatment (non-EA control group), 2 Hz EA group, and 100 Hz EA group. EA treatment at different frequencies can produce different levels of analgesia and hence the effect of EA with different frequencies on glaucoma treatment was investigated. Both eyes of each rat in the EA experimental groups received 3 EA treatment sessions each week for 4 weeks. The retinal function was measured using mfERG after 4 weeks of EA treatment. RESULTS: There was no significant difference in the amplitude (both N1 trough and P1 peak) of mfERG firstorder kernel response between the treatment and control groups. In determining the waveform characteristics by the ratio of N1 amplitude to P1 amplitude (N/P ratio), obvious differences were found in the N/P ratio between the control eyes and the glaucoma eyes in the non-EA group and the 100 Hz EA treatment group, but similar values in the N/P ratio were observed between the control eyes and the glaucoma eyes in the 2 Hz EA treatment group. The waveform from the eyes with glaucoma was deformed in both the non-EA group and the 100 Hz EA group, but the waveform from the glaucomatous eye was preserved in the 2 Hz EA group. CONCLUSIONS: Application of EA at 2 Hz provides neuroprotection by preserving retinal function in rats with experimental glaucoma. Low frequency EA may be an alternative therapy in the treatment of glaucoma.

Animals↗

PubMed2005

Effect on quality of life in patients with pityriasis rosea: is it associated with rash severity?

BACKGROUND: It is unknown how the quality of life (QOL) is affected in patients with pityriasis rosea (PR), and whether it is related to rash severity. METHODS: We constructed a valid and reliable Cantonese version of the Dermatology Life Quality Index (DLQI). We recruited patients with PR, with atopic dermatitis and with acne vulgaris, and controls of the same sex and comparable age. We applied the DLQI and the Pityriasis Rosea Severity Score (PRSS) to the patients with PR, the DLQI and the SCORing Atopic Dermatitis Index (SCORAD) to the controls with atopic dermatitis, and the DLQI and the Leeds Acne Grading System (LAGS) to the controls with acne vulgaris. RESULTS: Total DLQI scores of the 22 patients with PR (mean: 6.36, SD: 5.79) were significantly lower than those of the 22 controls with atopic dermatitis (mean: 12.00, SD: 5.38) (P = 0.021), but were insignificantly different from those of the 22 controls with acne vulgaris (mean: 6.86, SD: 4.53) (P = 0.57). Correlation between the total DLQI and PRSS scores was weak (gamma(s) = +0.19) and insignificant (P = 0.40). All six DLQI parameters were insignificantly correlated with the PRSS scores. In contrast, the total DLQI scores and most of the DLQI parameters were strongly correlated with the rash severity scores for the control subjects. Significantly more patients with PR have concerns regarding disease etiology and infectivity. CONCLUSIONS: The QOL of the patients with PR was significantly less affected than that for the patients with atopic dermatitis, but was insignificantly different from the patients with acne vulgaris. Unlike atopic dermatitis and acne vulgaris, the effects on the QOL in PR are insignificantly correlated with rash severity. These results bear important implications on clinical management.

Acne Vulgaris↗

PubMed2005

Multifocal electroretinography in isolated arterially perfused bovine eye.

AIM: To develop an isolated arterially perfused bovine eye as an in vitro model for studying retinal electrophysiology using multifocal electroretinography (mfERG). METHODS: Fresh bovine eyes were cannulated through the ophthalmic artery and perfused with oxygenated Krebs' solution at 37 degrees C within 15 min postmortem. Multifocal ERG was recorded using the veris 1.0 (Visual Evoked Response Imaging System). RESULTS: The mfERG waveform of in vitro bovine eyes had a typical trough (negative wave, N1) and peak (positive wave, P1) similar to those of human mfERG. The implicit times (peak latencies) for N1 and P1 were 20 and 42 ms respectively, and the average response amplitude (N1P1) was 55 nV. The implicit times of N1 and P1 were maintained for more than 4 h. The mfERG responses were affected proportionately by the stimulus intensity. Without a neutral density filter, the mean response amplitude was about 55 nV, which was diminished to 26, 18 and 10 nV under neutral density filters of 0.4, 1.0 and 1.4, respectively. Partial occlusion of the pupil completely abolished mfERG responses from the corresponding part of the retina. CONCLUSIONS: Isolated arterially perfused bovine eye may be used as an experimental model to study retinal electrophysiology using mfERG. The in vitro eye may offer a convenient and easily obtainable alternative to live animals, particularly for drug screening and invasive studies.

Animals↗

PubMed2004

Use of 1,320 nm Nd:YAG laser for wrinkle reduction and the treatment of atrophic acne scarring in Asians.

BACKGROUND AND OBJECTIVES: The role of 1,320 Nd:YAG in non-ablative skin rejuvenation in Asians is has not been established. Furthermore, no study has investigated the effectiveness of 1,320 Nd:YAG laser in the treatment of atrophic scarring in Asians. The objective of our study was to investigate the effectiveness of 1,320 Nd:YAG laser in wrinkle reduction and the treatment of atrophic acne scarring in Asians. STUDY DESIGN/MATERIALS AND METHODS: Twenty-seven female patients were included in the study: seven were treated for acne scarring and the others for wrinkle reduction. A 1,320 nm Nd:YAG laser (Cooltouch II, Roseville, CA) was used to treat both the cheeks and forehead for the patients with wrinkles, and both cheeks only for patients with atrophic acne scarring. All patients received treatment in the post-auricular areas. A spot size of 10 mm was used, and three passes were performed (two pre-cooling and one post-cooling). Patients were treated monthly for 6 months. All patients were subjectively assessed before and after their last treatment sessions using a structured questionnaire, and objectively assessed by the use of clinical photographs for by independent observers. A cutometer was used to assess viscoelasticity, and biopsies were taken at the post-auricular site for assessment by a pathologist. RESULTS: The overall degree of patients' satisfaction was rated as 4.9 (range 0-9.8) for wrinkle reduction and 4 (range 0-10) for acne scarring. In terms of objective assessment by independent observers, the degree of improvement was considered to be mild or no change in most cases. The independent pathologist who assessed the degree of improvement in terms of increased collagen production detected no change in 8 patients, mild improvement in 9, and moderate improvement in 10. There was also improvement in term of epidermal thickness in 13 cases. Assessment by viscoelasticity indicated a significant degree of improvement in most parameters in both groups of patients. Blistering occurred in five cases, all in the central facial areas, and post-inflammatory hyperpigmentation occurred in three cases. All cases of PIH resolved after the use of 4% hydroquinoine. There was no scarring or hypopigmentation. CONCLUSIONS: The 1,320 nm Nd:YAG laser is effective for wrinkle reduction and atrophic acne scar improvement, but to further enhance the clinical outcome a combination approach with another device such as IPL and a surgical technique such as subcision is necessary.

Acne Vulgaris↗

PubMed2004

Is human herpesvirus 7 the causative agent of pityriasis rosea?--A critical review.

BACKGROUND: Conflicting results on the association of pityriasis rosea and human herpesvirus 7 infection have been reported by different investigators. AIM: To review the level of evidence for such an association. METHODS: Medline was searched with unlimited data entry and 13 reports were retrieved. The data were analyzed for a causative association according to the criteria of Fredericks and Relman, which take into consideration latent infection and the reactivation of viruses characteristic of herpesviruses, and the roles of sequence-based detection methods. RESULTS: None of the criteria was substantiated by the findings of most investigators. Factors leading to the discrepancies of the results were discussed. CONCLUSION: There is currently insufficient evidence that human herpesvirus 7 infection is causally related to pityriasis rosea.

DNA, Viral↗

PubMed2003

Role of skin cooling in improving patient tolerability of Q-switched Alexandrite (QS Alex) laser in nevus of Ota treatment.

BACKGROUND: The development of a high-energy laser device with very short pulse duration has revolutionized the treatment of nevus of Ota. Nevertheless, patients still suffer from complications that range from the pain and swelling that occur immediately after laser surgery to post-operative pigmentary changes and scarring. However, the simultaneous use of skin surface cooling and laser surgery may limit the damage of non-target tissue. OBJECTIVES: To assess whether epidermal cooling reduces the pain and swelling that commonly occur after laser treatment for nevus of Ota. STUDY DESIGN/PATIENTS AND METHODS: Thirty-seven patients with nevus of Ota were recruited from a dermatology outpatient clinic. Before treatment, the research nurse used an ink pen to divide the lesions into two halves. Half of each lesion was treated with a Q-switched Alex laser system that had a cool sapphire plate in contact as a mean of skin cooling. The other half was treated with the same laser, but with the cooling device switched off. Immediately after treatment, and again 1 week later, the patients answered a questionnaire, which assessed the symptoms that are associated with laser surgery. Dose assessment was performed in each half of the nevus to obtain the optimal fluence that could be used for the treatment of nevus of Ota before the entire half was treated. RESULTS: There was no difference in terms of the optimal fluence that was used, but in terms of immediate pain the patients associated the side that was treated with the cooling plate with a significantly lesser degree of pain than the non-cooled side (P = 0.001). Eighty two percent of the patients preferred the cooled side to the non-cooled side. CONCLUSIONS: Pre- and post-operative skin cooling is effective in improving the tolerability of nevus of Ota patients to Q-switched laser treatment. However, the use of cooling during laser treatment of nevus of Ota did not allow the use of higher fluence.

Adult↗

PubMed2003

In vitro study examining the effect of sub-lethal QS 755 nm lasers on the expression of p16INK4a on melanoma cell lines.

BACKGROUND AND OBJECTIVES: Q-switched lasers had been used in the treatment of lentigo maligna but their role remains controversial. While previous studies have addressed the change in adhesion molecule expression after sub-lethal laser damage, no study has addressed the impact of sub-lethal laser damage at a molecular level. The p16 gene has been proposed as the candidate gene for melanoma. Our objective is to examine the effect of sub-lethal laser damage on p16 expression in melanoma cell lines. STUDY DESIGN/MATERIALS AND METHODS: Three human melanoma cell lines-HTB 66, Sk-mel-24 (HTB 71), and G361-were irradiated by a Q-switched 755 nm Alexandrite laser at fluencies that ranged from 0.85 to 2.0 J/cm(2). HTB 66 was the only cell line with significant expression of p16INK4a while the other two cells lines were p16INK4a negative and served as negative control. Protein and mRNA expression for p16 were assessed by flow cytometry and RT-PCR, respectively. RESULTS: The level of p16INK4a protein in cell line HTB 66 increased significantly after laser irradiation as compared with non-irradiated cells. The level of p16INK4a protein did not change in p16INK4a-negative cell lines (Sk-mel-24 and G361). However, there was only a slight increase in the percentage of G0/G1 phase cells. CONCLUSIONS: Sub-lethal laser damage could increase DNA damage leading to an increase in p16 expression, and such effect would be particularly undesirable for patients with p16 mutation. Further studies are warranted to examine the role of sub-lethal laser damage in inducing p16 mutation.

Analysis of Variance↗

PubMed2003

Use of Q-switched ruby laser in the treatment of nevus of ota in different age groups.

BACKGROUND AND OBJECTIVES: Nevus of Ota is a form of dermal melanocytic hamartoma that appears as a bluish discoloration in the trigeminal region. Although Q-switched lasers provide effective treatment, the appropriate age at which to start that treatment is not known. Our aim is to compare the clinical efficacy and safety of Q-switched ruby laser (QSRL) in the treatment of nevus of Ota in different age groups. STUDY DESIGN/MATERIALS AND METHODS: Our study included 46 children and 107 adults with nevus of Ota, which had been treated with QSRL that achieved excellent (75% or more) to complete response. The laser parameters were 694-nm wavelength, 30 nanoseconds pulse duration, 4-mm spot size, and 5-7 J/cm2 fluence at 3-4 month intervals. We assessed the mean number of treatment sessions and the degree of complications in the two age groups of patients. RESULTS: The mean number of treatment sessions to achieve significance to complete clearing was 3.5 for the younger age group and 5.9 for the older age group (P = 0.0001). The complication rate for the younger age group was 4.8% as compared to 22.4% for the older age group. CONCLUSIONS: The use of QSRL for the treatment of nevus of Ota in children can achieve an excellent result in fewer sessions and at a lower complication rate than later treatment. The risk of recurrence is a concern, however, and further long-term study is necessary to address this issue.

Adolescent↗

PubMed2003

Treatment of phacomatosis pigmentovascularis: a combined multiple laser approach.

BACKGROUND: Phacomatosis pigmentovascularis (PPV) consists of a capillary malformation with a variety of melanocytic lesions, which involve various regions of the body and are difficult to treat with conventional therapeutic tools. OBJECTIVE: We described two cases with PPV (type IIa and IIb) that were successfully treated with different lasers. METHODS: The areas involved by both melanocytic lesions and port-wine stains were treated using the Q-switched ruby laser, the Q-switched Alexandrite laser, and the flashlamp pumped pulsed-dye laser. RESULTS: Removal of a good portion of cutaneous and vascular lesions using combined multiple laser approach was achieved after 6 sessions in the first case under general anesthesia and after 31 sessions under local anesthesia in the second case. CONCLUSION: PPV type II can be treated successfully by laser treatment. We prefer to start combined multiple laser treatment of PPV in childhood period under general anesthesia because it will reduce the number of treatment, improve the patient's quality of life, and increase the cost-effectiveness of the treatment.

Adult↗